After years of speculation, decades actually, and several false alarms, Nebraska will be getting a third area code for general telephone service. (Isn't this exciting? Yeah, right!)
The number of available prefixes in 402 is really-truly approaching exhaustion, even with a judicious degree of sharing of many prefixes between providers. (Yes, you can now get an 'Omaha' cell phone with a 'Springfield' prefix of 402-253!)
NPA (Area Code) 531 will go live in early 2011, overlaying the area currently served by Nebraska's original area code, 402, which now serves Omaha, Lincoln, and several 'nearby' communities such as Hastings, Norfolk, and Valentine.
This time it's really gonna happen, and conditioning of the Teeming Millions for the impending transition is scheduled to begin Real Soon Now.
The Powers That Be decided some time ago that it is For Our Own Good that 531 should be overlaid on 402 rather than split geographically, thus saving half of us the trauma of remembering a new area code.
This will 'require' (explaining why this is really not the case will be an exercise for the student) that local calls within the 402 area must be dialed using ten digits: the area code, the prefix, and the line number. (10 - Count 'Em - 10 NPA-NXX-XXXX)
To phase in the new area code, 'permissive' dialing, which means that you are allowed to dial with ten digits if you really insist, will begin next month in June. Mandatory 10 digit dialing will begin in February, 2011, clearing the way for NPA 531 deployment in March.
Fortunately, one vestige of sanity remains. The Powers That Be have decided that we will not be required to dial '1' to prefix all calls, keeping with the notion (sort of) that '1 means toll.'
The explosion in growth of cellular phones in the 1990s brought this on, and even though it was put off a number of times, it looks like we're now stuck with it.
This was not the first time, however, that AC 402 was broken up.
What we know as Area Codes, actually Numbering Plan Areas (NPAs), were assigned in the 1940s as Ma Bell migrated from manual long-distance service to operator-assisted machine-switched long-distance service, facilitated by the barely-pre-war XBT (Crossbar Tandem) and the post-war #4 Toll Crossbar switch.
Nebraska was originally assigned NPA 402, serving all of Nebraska at the time. Many states, some far more populous than Nebraska was back then, were served by a single area code. In those days, true NPA-NNX-XXXX compliant phone numbers were far from universal. Many larger cities still used 6-digit 2-4 numbering plans. Omaha had such a plan until September 10, 1960. Council Bluffs had a combined 4-5 digit plan, as did many other communities with two or three COs.
As communities adopted the then NPA-NNX-XXXX standard (NPA-NXX was yet to come) in the 1950s, a necessary prerequisite for inbound Direct Distance Dialing, available prefixes were quickly exhausted and several area code 'splits' occurred in the early-mid 1950s. A severely gerrymandered line was drawn arbitrarily across Nebraska, leaving communities such as Rulo, in the southeast corner and Valentine, in northwest Nebraska, as well as Omaha and Lincoln in 402, with everything else in 308.
The phase-in of NXX prefixes in the late 1960s delayed several area code splits, and the sharing of NXXs among providers held things off even further, but countless splits and overlays occurred in the 1990s and 2000s, and we will be one of them soon.
Aren't we excited ??
Oh, one last thing. Let's be sure to notice how our local Talking Heads screw up the details of this as the date approaches. Ted Brockman, are you listening in? ;-)
Thursday, May 13, 2010
Saturday, May 1, 2010
Mayday! Mayday! Mayday!
It's Mayday! Saturday, May 1, and I and a friend set off in the direction of Lyons, NE to visit the Lyons Regional Antique Telephone Show, jointly sponsored by the JKL Museum Of Telephony and the Telephone Collectors International Society.
It's an easy drive from Omaha. We stopped and had breakfast in Fremont and arrived at the site before noon.
The show site is the former AT&T Long Lines 'Hardened' Lyons Communication Center, built to withstand a nuclear blast and then some. The site is very easy to find. Just drive in the direction of Lyons, and look for the tower. ;-)
As a reformed phr^H^H^Htelephone enthusiast, I thought my days of 'underground' phone business were over. WRONG!
The show was, literally, three stories down in a blast-proof bay.
The huge blast door was open for the occasion.
The facility is, literally, a cold-war vintage communication center.
Most of the equipment has obviously been removed, but the remnants of what appear to be a MDF remain.
As well as a few items on display.
But anyway, back to the show ...
On my personal 'wish list' were a few specific items:
I must admit that most of what I saw at the show was 'good junk', as opposed to 'junk junk', as most of those showing/selling stuff appeared to be sincere collectors and not obvious rip-off artists.
I was able to score a restorable 202 with a good condition dial and E series handset, and a very good, but obviously repainted 302. Two out of four ain't bad. ;-)
Let's take a look at a few things I wanted, but did not buy.
There were a few nice original WECO candlesticks, with dial, and cosmetically and mechanically good or better.
However, the price points were just far more than I was willing to pay. :-(
There were some very nice clear sets, this one being an AE Monophone,
and this one being a WECO Princess, but unfortunately these were for show only and not for sale.
On the back of a truck outside the building was an old WECO cord board. I'm kind of assuming that this was out here because of the difficulty in getting it down the steps.
Those from Omaha will immediately recognize the name of the business from which it came. ;-)
For some reason, they are saying that this will be the last show of this type at the Lyons facility. I'm not sure why, but I do wish they would reconsider this decision. :=(
Anyway, it was time well spent !!
It's an easy drive from Omaha. We stopped and had breakfast in Fremont and arrived at the site before noon.
The show site is the former AT&T Long Lines 'Hardened' Lyons Communication Center, built to withstand a nuclear blast and then some. The site is very easy to find. Just drive in the direction of Lyons, and look for the tower. ;-)
As a reformed phr^H^H^Htelephone enthusiast, I thought my days of 'underground' phone business were over. WRONG!
The show was, literally, three stories down in a blast-proof bay.
The huge blast door was open for the occasion.
The facility is, literally, a cold-war vintage communication center.
Most of the equipment has obviously been removed, but the remnants of what appear to be a MDF remain.
As well as a few items on display.
But anyway, back to the show ...
On my personal 'wish list' were a few specific items:
- A working or easily restorable 'candlestick' desk set, with a working dial, preferably original WECO, but maybe Kellogg or others. No repros or bastardized sets.
- A working or easily restorable 202 series desk set, with working dial.
- A VG or better 302 desk set.
- A clear-case 500, 1500, or 2500 set.
I must admit that most of what I saw at the show was 'good junk', as opposed to 'junk junk', as most of those showing/selling stuff appeared to be sincere collectors and not obvious rip-off artists.
I was able to score a restorable 202 with a good condition dial and E series handset, and a very good, but obviously repainted 302. Two out of four ain't bad. ;-)
Let's take a look at a few things I wanted, but did not buy.
There were a few nice original WECO candlesticks, with dial, and cosmetically and mechanically good or better.
However, the price points were just far more than I was willing to pay. :-(
There were some very nice clear sets, this one being an AE Monophone,
and this one being a WECO Princess
On the back of a truck outside the building was an old WECO cord board. I'm kind of assuming that this was out here because of the difficulty in getting it down the steps.
Those from Omaha will immediately recognize the name of the business from which it came. ;-)
For some reason, they are saying that this will be the last show of this type at the Lyons facility. I'm not sure why, but I do wish they would reconsider this decision. :=(
Anyway, it was time well spent !!
Thursday, March 25, 2010
The Ad Man Cometh
Let's take a break from the techie stuph, and reflect on another aspect of Ma Bell's omnipresence during her heyday, some vintage Ma Bell ads, compiled from various sources.
Yellow Pages<tm>.
I guess this one was before you let your fingers do the walking.
'Hey Joe, where ya goin' with that phone in your hand?'
But seriously, in these days we take for granted that circuits, whether subscriber loops or international long-haul trunks, are plentiful and always at your beck and call. In the WWII era, party lines, 4 and 8 party in Ma Bell land, up to 12 party in Indie land, were commonplace. Long Distance trunks were in many cases scarce and in high demand.
Ads such as this were common, and rightly so, encouraging subscribers to keep the lines open for servicemembers during the peak evening hours.
Many of Ma Bell's vintage ads feature anthropomorphic and larger-than-life phones.
This one has to be Ma Bell's answer to Reddy Kilowatt. ;-)
They were bragging about a 'short' two-minute time to set up a LD call. Remember, this was back in the days when Long Distance was totally manual. The calls had to be manually worked through Ma Bell's network, often through one or more intermediary offices, and through an 'inward' Long Distance operator at the far end.
These two ads (above and below) feature similar sets of what I would call an unusual configuration, 200 series sets with F series handsets, no dial.
These had to be from the era when manual service was still standard and presumed to be what the majority of the viewers of the ads were accustomed to. I never experienced manual service first hand, but I do know that it was commonplace, even in some parts of major metropolitan areas, into the 1950s. I would guess the vintage of the ad immediately above to be 1930s, showing the 'high tech' F handset, but not rubbing it in to the noses of the viewers that dial service was not available in many areas.
This is also the earliest ad I've seen where the '2368' number was used.
Although the number tag is not entirely shown, it's obvious from the spacing that it's intended to be EX-2368 and not something like EX3-2368. The 2-4 numbering pattern was very common in the 1930s in areas served by both manual offices and newer 'machine switching' offices.
Hmmmm .... I wonder if, during the heyday of Ma Bell's manual service, they had offices such as QUigley or QUeensbridge or ... ;-)
The family at EX-2368 gets a new 302 set, and my guess is that this ad is late 1940s, with 2-4 dialing still commonplace, but before the 500 series was common.
The number morphs to Main 0-2368 in this ad featuring the 302.
And in this featuring the 500.
Phone 'enthusiasts' will be quick to point out that zero, as the third digit of the office code (NNX) was not allowed until the late 1960s.
As I said ...
... the quality of the voice in Ma Bell's glory days was second to none! As critical as I've been of Ma over the years, this is the one thing I admit was superior during the days of one system, one solution.
Likewise ...
The quality of the sets was second to none as well! The 500 was built like a tank. It could take any kind of abuse that an ornery kid, an angry parent, or a curious phr^H^H^Henthusiast could ever deliver. I think the MTBF (mean time between failures) of a late 60s vintage 500 was measured in centuries!
(We now return to our regular program.)
Tell the kids that 'Uncle Jim' is coming over (but he's not really your uncle).
'Hi baby! He's gone and won't be back until tomorrow night. C'mon over. The kids are, uh, occupied!' ;-)
My Aunt had a Princess<tm> phone in her bedroom, early model, sky-blue pink IIRC, rotary dial, maybe 1961 or so.
This one did not have a ringer in the set. It was on the baseboard, color-coordinated with the set, almost like a throwback to the 202 days. It had that lighted dial, powered by the 'brick on a string' transformer plugged into the wall socket.
Then about 1967 Mom got a Princess phone. This one was again rotary dial, but had the ringer in the set. She refused to let the installer staple a line for the light across the baseboard to a 'brick on a string' at the nearest wall socket, which was way across the room, so at the time of installation, this Princess was dark.
It's always handy having a son who was a budding phr^H^H^Hphone enthusiast! I found the correct run of quad down in the cellar, carefully dissected it with the X-acto knife, pieced out the yellow/black pair and connected it to the building's 24 volt doorbell transformer, but with a 'one goes out they all go out' series Christmas lamp in each leg as a ballast and to protect from any shorts. Hey, we don't want a meltdown of 100' of quad in a wall, do we? ;-)
Let there be light!
It worked just fine and I was her hero -- for maybe a day or so. ;-)
It was there and working until they moved out some years later. I never de-installed it. Hey, after they moved it was no longer my problem, right? ;-) I'm sure that TPC would have had a cow if they ever came upon it.
Phoning is fun !!
Just pick up Mommy's phone, dial 1-2-3-4-5-6-7-8 and listen to the recording, rinse, repeat. ;-)
'{sigh} Was it as good for you as it was for me?' ;-)
This is a rather unusual set for the bedroom.
The baby blue 500 is appropriate for the boudoir I admit. So is the rarely-seen dial light (available for a semi-reasonable monthly charge), but notice the two-line turn-key.
Maybe it's so she can listen in on the Teenline<tm> after they are supposed to be asleep! ;-)
Bedroom phones were promoted heavily during the 1950s and 1960s.
As well as extension phones anywhere.
'Congratulations again, Mrs. Bratter, and may there be many extensions!' ;-)
Phones in color!
Notice the straight, non-coiled handset cables. Coiled cables 'spring cords' were optional, with a recurring monthly charge, into the 1960s.
Speaking of which ...
Where does the handset cable terminate?
Your phone away from home.
In this day and age, we think of the pay phone as being in the same category as the dodo bird and the Oldsmobile. They are becoming few and far between.
'Mommy, what's a phone booth?'
If the pay phone is an endangered species, the phone booth is essentially extinct in the wild! You just don't see these anymore.
Back in the days, Ma Bell did promote the comfort and convenience of the pay phone, in the privacy of your own phone booth.
And a local call was only a dime! Cheaper if you had a straight pin and knew how to use it! ;-)
Hey! Curb your dog, Missy!
How handy ...
... a 500 on the patio by the lake!
Wasn't this the thing that Dr. Brown was wearing on his head in the first BTTF?
The Fone Man cometh!
'Hi, my name's Krusty, and I'm from The Fone Company. Let's go into the bedroom so I can {wink-wink} install my cable.' ;-)
302G-3F
Standard issue from around WWII until the mid 1950s.
Is it my imagination, or does that box appear too small for the set and the handset?
I hope you enjoyed today's little digression.
Yellow Pages<tm>.
I guess this one was before you let your fingers do the walking.
'Hey Joe, where ya goin' with that phone in your hand?'
But seriously, in these days we take for granted that circuits, whether subscriber loops or international long-haul trunks, are plentiful and always at your beck and call. In the WWII era, party lines, 4 and 8 party in Ma Bell land, up to 12 party in Indie land, were commonplace. Long Distance trunks were in many cases scarce and in high demand.
Ads such as this were common, and rightly so, encouraging subscribers to keep the lines open for servicemembers during the peak evening hours.
Many of Ma Bell's vintage ads feature anthropomorphic and larger-than-life phones.
This one has to be Ma Bell's answer to Reddy Kilowatt. ;-)
They were bragging about a 'short' two-minute time to set up a LD call. Remember, this was back in the days when Long Distance was totally manual. The calls had to be manually worked through Ma Bell's network, often through one or more intermediary offices, and through an 'inward' Long Distance operator at the far end.
These two ads (above and below) feature similar sets of what I would call an unusual configuration, 200 series sets with F series handsets, no dial.
These had to be from the era when manual service was still standard and presumed to be what the majority of the viewers of the ads were accustomed to. I never experienced manual service first hand, but I do know that it was commonplace, even in some parts of major metropolitan areas, into the 1950s. I would guess the vintage of the ad immediately above to be 1930s, showing the 'high tech' F handset, but not rubbing it in to the noses of the viewers that dial service was not available in many areas.
This is also the earliest ad I've seen where the '2368' number was used.
Although the number tag is not entirely shown, it's obvious from the spacing that it's intended to be EX-2368 and not something like EX3-2368. The 2-4 numbering pattern was very common in the 1930s in areas served by both manual offices and newer 'machine switching' offices.
Hmmmm .... I wonder if, during the heyday of Ma Bell's manual service, they had offices such as QUigley or QUeensbridge or ... ;-)
The family at EX-2368 gets a new 302 set, and my guess is that this ad is late 1940s, with 2-4 dialing still commonplace, but before the 500 series was common.
The number morphs to Main 0-2368 in this ad featuring the 302.
And in this featuring the 500.
Phone 'enthusiasts' will be quick to point out that zero, as the third digit of the office code (NNX) was not allowed until the late 1960s.
As I said ...
... the quality of the voice in Ma Bell's glory days was second to none! As critical as I've been of Ma over the years, this is the one thing I admit was superior during the days of one system, one solution.
Likewise ...
The quality of the sets was second to none as well! The 500 was built like a tank. It could take any kind of abuse that an ornery kid, an angry parent, or a curious phr^H^H^Henthusiast could ever deliver. I think the MTBF (mean time between failures) of a late 60s vintage 500 was measured in centuries!
(We now return to our regular program.)
Tell the kids that 'Uncle Jim' is coming over (but he's not really your uncle).
'Hi baby! He's gone and won't be back until tomorrow night. C'mon over. The kids are, uh, occupied!' ;-)
My Aunt had a Princess<tm> phone in her bedroom, early model, sky-blue pink IIRC, rotary dial, maybe 1961 or so.
This one did not have a ringer in the set. It was on the baseboard, color-coordinated with the set, almost like a throwback to the 202 days. It had that lighted dial, powered by the 'brick on a string' transformer plugged into the wall socket.
Then about 1967 Mom got a Princess phone. This one was again rotary dial, but had the ringer in the set. She refused to let the installer staple a line for the light across the baseboard to a 'brick on a string' at the nearest wall socket, which was way across the room, so at the time of installation, this Princess was dark.
It's always handy having a son who was a budding phr^H^H^Hphone enthusiast! I found the correct run of quad down in the cellar, carefully dissected it with the X-acto knife, pieced out the yellow/black pair and connected it to the building's 24 volt doorbell transformer, but with a 'one goes out they all go out' series Christmas lamp in each leg as a ballast and to protect from any shorts. Hey, we don't want a meltdown of 100' of quad in a wall, do we? ;-)
Let there be light!
It worked just fine and I was her hero -- for maybe a day or so. ;-)
It was there and working until they moved out some years later. I never de-installed it. Hey, after they moved it was no longer my problem, right? ;-) I'm sure that TPC would have had a cow if they ever came upon it.
Phoning is fun !!
Just pick up Mommy's phone, dial 1-2-3-4-5-6-7-8 and listen to the recording, rinse, repeat. ;-)
'{sigh} Was it as good for you as it was for me?' ;-)
This is a rather unusual set for the bedroom.
The baby blue 500 is appropriate for the boudoir I admit. So is the rarely-seen dial light (available for a semi-reasonable monthly charge), but notice the two-line turn-key.
Maybe it's so she can listen in on the Teenline<tm> after they are supposed to be asleep! ;-)
Bedroom phones were promoted heavily during the 1950s and 1960s.
As well as extension phones anywhere.
'Congratulations again, Mrs. Bratter, and may there be many extensions!' ;-)
Phones in color!
Notice the straight, non-coiled handset cables. Coiled cables 'spring cords' were optional, with a recurring monthly charge, into the 1960s.
Speaking of which ...
Where does the handset cable terminate?
Your phone away from home.
In this day and age, we think of the pay phone as being in the same category as the dodo bird and the Oldsmobile. They are becoming few and far between.
'Mommy, what's a phone booth?'
If the pay phone is an endangered species, the phone booth is essentially extinct in the wild! You just don't see these anymore.
Back in the days, Ma Bell did promote the comfort and convenience of the pay phone, in the privacy of your own phone booth.
And a local call was only a dime! Cheaper if you had a straight pin and knew how to use it! ;-)
Hey! Curb your dog, Missy!
How handy ...
... a 500 on the patio by the lake!
Wasn't this the thing that Dr. Brown was wearing on his head in the first BTTF?
The Fone Man cometh!
'Hi, my name's Krusty, and I'm from The Fone Company. Let's go into the bedroom so I can {wink-wink} install my cable.' ;-)
302G-3F
Standard issue from around WWII until the mid 1950s.
Is it my imagination, or does that box appear too small for the set and the handset?
I hope you enjoyed today's little digression.
Monday, March 22, 2010
Transmission Zones
As critical as I am of Ma Bell, the one thing I must admit is that the quality of the voice signal during Ma Bell's heyday is the best it's ever been during the age of telephony.
The clarity of the voice transmitted by the Bell System between the 1920s and the 1980s was in most cases far superior to that of today's typical phone call.
Back then, from the era of the 202 with the E series handset, to the phase-out of the 500/2500 and (real) Trimline, we didn't need MOS scores! 5.0 was expected and with rare exception, delivered.
If you had an issue, they would cheerfully fix it, with none of this "If the trouble is in your inside wire, a $2500.00 service charge may apply ..." nonsense. (You did need to remember, of course, to unplug and hide that stray 302, you know, the one with the ringer disconnected, before TPC showed up.) ;-)
The 'cheapie chirper' phone of the early 1990s could never reproduce the voice as clearly as the 500, or even the 302. Even the 'cheapie chirpers' put today's cell phones to shame as far as voice quality is concerned. Of course, toward the bottom of the call clarity food chain are such things as Magic Jack and Skype.
Bell: Wats n, cm hr, I wnt o.
Watson: What? Huh? Say again? Eh? Pardon?
The sets were built like tanks as well. You could literally heave a 500 into a brick wall with only cosmetic damage. Try that with your Mallard Duck phone!
The quality of the voice was paramount to Ma Bell. Many guidelines for provisioning and maintenance were set up to assure voice quality.
In today's world, no matter where you live, no matter how far from the CO, SLC, or ONU pedestal, you don't really care. You buy (or otherwise acquire) a set, plug it in, and talk, or at least attempt to do so.
Back in the heyday of The System, the distance of the wire from the subscriber to the CO fell into one of a number of 'Transmission Zones', each with its own particular needs and characteristics. Originally (or so they tell me) there were several zones: 1, 2, 3, 4, and 5. By the early 1960s or so, they settled into three more broadly-defined zones: Zone 2, Zone 5, and Zone L.
Zone 2 was the closest to the CO, and was the set of subscribers within a 10,000 foot loop length (or so) the the CO. A TPC employee with whom I was acquainted told me to the effect of "we never use these anymore, but back then we estimated Zone 2 as about two miles, as the crow flies, from the CO." Zone 2 was where the loop was short, relatively free of electrical interference and distance-specific transmission loss, and the loop current was relatively high.
Zone 5 was farther out, and in the old days often estimated as "between two and five miles or so from the CO, as the crow flies, but who would want to fly with an old crow!"
If you draw circles on a map, you'll see that a very significant percentage of subscribers fell into Zone 2. Metropolitan CO boundaries typically overlapped in Zone 2 or Zone 5.
Zone L was roughly defined as anything more than about five miles out or so, or alternatively "where you get far out enough that you start having trouble", out to the limit of where things just would not work, even with range boosters, CO long-line equipment, and in-set amplifiers.
The following chart, which appeared in some similar versions in various Ma Bell internal publications at the time, illustrates the zones and recommended station equipment for each.
(This chart also illustrates what's sometimes called the 'Shirley Temple Principle', you can never be too cute!) ;-)
I would estimate this version to be ca. 1963, after the announcement of the Trimline, but before the 302 was out of use.
Note that this chart recommends that 302 sets be confined to Zone 2, short loops only. For many years, the 302 was standard issue in what the chart calls Zone 5 and even in Zone L. From 1949 or so, the newer network in the 500 series sets did give better performance on medium-long to very long loops.
However, notice that the 500, restrained by the ball and chain, is not encouraged in Zone 2.
Historically, that's because the earliest 500 sets, those equipped with the model 425A network, did not perform very well on short loops. They often had very loud sidetone and distorted received audio.
The work-around was to install a type 311A Equalizer on early 500 sets used on short loops. This was shoehorned under the dial toward the left of the base, as viewed from the front.
The 'equalizer' was an add-on to the early 500 series sets with the older internal networks, those lacking the varistor compensation which compensated for short loops and high loop current. The 311A Equalizer was said by those in the know to be an incandescent lamp, used as a makeshift varistor, to improve the performance on short loops.
The newer 425x networks included varistor compensation and worked equally well on loops from a few feet to several miles in length.
That's just peachy for short loops, but what about long loops?
The chart above makes reference to a '238A Amplifier', and that was one of a handful of similar devices.
The 238A was a one-transistor device, constructed around a G series transmitter mounting cup, which was designed to boost the outgoing transmitted audio and compensate for the long loop.
The 238A (and successors) were commonplace on long loops (Zone L) into the 1980s.
The 276A was an improved and somewhat beefier version of the 238A.
For those who truly speak geek, the schematic of the 276A Amplifier is shown below.
The transmitter in series with the inductor is capacitively coupled to the base of the transistor, and the emitter-collector of the transistor replaces the transmitter with respect to the network.
The 238A was very similar.
Other variations existed. The 277, for example, incorporated a polarity guard in the form of a bridge rectifier. This was to be used with switching equipment which reversed battery to the calling set upon far-end supervision.
The clarity of the voice transmitted by the Bell System between the 1920s and the 1980s was in most cases far superior to that of today's typical phone call.
Back then, from the era of the 202 with the E series handset, to the phase-out of the 500/2500 and (real) Trimline
If you had an issue, they would cheerfully fix it, with none of this "If the trouble is in your inside wire, a $2500.00 service charge may apply ..." nonsense. (You did need to remember, of course, to unplug and hide that stray 302, you know, the one with the ringer disconnected, before TPC showed up.) ;-)
The 'cheapie chirper' phone of the early 1990s could never reproduce the voice as clearly as the 500, or even the 302. Even the 'cheapie chirpers' put today's cell phones to shame as far as voice quality is concerned. Of course, toward the bottom of the call clarity food chain are such things as Magic Jack and Skype.
Bell: Wats n, cm hr, I wnt o.
Watson: What? Huh? Say again? Eh? Pardon?
The sets were built like tanks as well. You could literally heave a 500 into a brick wall with only cosmetic damage. Try that with your Mallard Duck phone!
The quality of the voice was paramount to Ma Bell. Many guidelines for provisioning and maintenance were set up to assure voice quality.
In today's world, no matter where you live, no matter how far from the CO, SLC, or ONU pedestal, you don't really care. You buy (or otherwise acquire) a set, plug it in, and talk, or at least attempt to do so.
Back in the heyday of The System
Zone 2 was the closest to the CO, and was the set of subscribers within a 10,000 foot loop length (or so) the the CO. A TPC employee with whom I was acquainted told me to the effect of "we never use these anymore, but back then we estimated Zone 2 as about two miles, as the crow flies, from the CO." Zone 2 was where the loop was short, relatively free of electrical interference and distance-specific transmission loss, and the loop current was relatively high.
Zone 5 was farther out, and in the old days often estimated as "between two and five miles or so from the CO, as the crow flies, but who would want to fly with an old crow!"
If you draw circles on a map, you'll see that a very significant percentage of subscribers fell into Zone 2. Metropolitan CO boundaries typically overlapped in Zone 2 or Zone 5.
Zone L was roughly defined as anything more than about five miles out or so, or alternatively "where you get far out enough that you start having trouble", out to the limit of where things just would not work, even with range boosters, CO long-line equipment, and in-set amplifiers.
The following chart, which appeared in some similar versions in various Ma Bell internal publications at the time, illustrates the zones and recommended station equipment for each.
(This chart also illustrates what's sometimes called the 'Shirley Temple Principle', you can never be too cute!) ;-)
I would estimate this version to be ca. 1963, after the announcement of the Trimline, but before the 302 was out of use.
Note that this chart recommends that 302 sets be confined to Zone 2, short loops only. For many years, the 302 was standard issue in what the chart calls Zone 5 and even in Zone L. From 1949 or so, the newer network in the 500 series sets did give better performance on medium-long to very long loops.
However, notice that the 500, restrained by the ball and chain, is not encouraged in Zone 2.
Historically, that's because the earliest 500 sets, those equipped with the model 425A network, did not perform very well on short loops. They often had very loud sidetone and distorted received audio.
The work-around was to install a type 311A Equalizer on early 500 sets used on short loops. This was shoehorned under the dial toward the left of the base, as viewed from the front.
The 'equalizer' was an add-on to the early 500 series sets with the older internal networks, those lacking the varistor compensation which compensated for short loops and high loop current. The 311A Equalizer was said by those in the know to be an incandescent lamp, used as a makeshift varistor, to improve the performance on short loops.
The newer 425x networks included varistor compensation and worked equally well on loops from a few feet to several miles in length.
That's just peachy for short loops, but what about long loops?
The chart above makes reference to a '238A Amplifier', and that was one of a handful of similar devices.
The 238A was a one-transistor device, constructed around a G series transmitter mounting cup, which was designed to boost the outgoing transmitted audio and compensate for the long loop.
The 238A (and successors) were commonplace on long loops (Zone L) into the 1980s.
The 276A was an improved and somewhat beefier version of the 238A.
For those who truly speak geek, the schematic of the 276A Amplifier is shown below.
The transmitter in series with the inductor is capacitively coupled to the base of the transistor, and the emitter-collector of the transistor replaces the transmitter with respect to the network.
The 238A was very similar.
Other variations existed. The 277, for example, incorporated a polarity guard in the form of a bridge rectifier. This was to be used with switching equipment which reversed battery to the calling set upon far-end supervision.
Friday, March 12, 2010
101 ESS
The 101 ESS was a model of telephone switch which played a very important part in Ma Bell's emerging technology, but it only appears in fleeting references in historical documents, eclipsed by the 1 ESS and others.
The 101 was Ma Bell's first! Yes, predating the 1E!
Some will tell you that the 101 ESS is essentially the red-headed stepchild of the Bell System. It was quirky, had a short operational life, and had a bad reputation in the field.
For the time, the 101 was ahead of its time, literally. It had many innovations which are reflected in the mature technology of today. It was the first 'stored program control' switching system used in commercial service. (More about that term below.) It was also the first switch to use TDM (Time Division Multiplexing) to switch voice paths. It was Ma Bell's first commercially-deployed switch which supported Touch-Tone.
The 101 began life in the 1950s as the EPBX project, Ma Bell's initiative to create a state-of-the-art all-electronic small telephone switch which could be deployed at a customer's premises in lieu of the very bulky, noisy, and space-consuming Step equipment, and the somewhat bulky Crossbar PBX systems.
It was renamed the 101 ESS after the term ESS was settled upon to be the service mark of Ma Bell's electronic switches. The number 101 was chosen since full-scale CO switches were normally assigned single-digit numbers, and PBX systems were normally assigned three-digit numbers. 101 was, of course, the lowest number available under those criteria.
The numbers vary as far as the line capacity of the 101. Some literature will cite limits in the hundreds of lines, others refer to low thousands of lines being available from later 101 systems.
The strategy was to place a large central control unit in the CO, acting as the equivalent of the line link section of an otherwise normal 5 Crossbar office, and a 'smart' remote unit at each customer's premises, connected by an appropriate number of signal and control trunks to the CO. To be commercially viable, each CO supporting 101 service had to serve a certain number of remote customers, 10 or so, depending on size and density.
The 101 service was sold under the service mark of 'Centrex-CU', the CU meaning that (some of) the switching equipment resided at the customer's premises. Centrex-CU included normal features such as direct inward dialing to four-digit extensions, direct outward 'dial 9' service with ANI (automatic calling number identification) with detailed reports and variable billing options, and such 'Custom Calling Features' such as speed dialing, call transfer, camp-on, remote pick-up of a ringing extension, call forwarding, and user-initiated 3-way and 4-way conference calling.
The 101 was also used for some stand-alone, non-DID PBX applications, but these were few and far between.
The technology used at the time for the 101 was discrete-component diode-transistor logic (DTL), making up the bulk of the electronics.
The switch fabric used an innovative but unusual form of analog time division multiplexing. Instead of multiple physical audio paths through the switch matrix, there was one path which was time-shared by all active calls, each being switched in and out at the rate of 12,000 samples per second. The actual 'switching' of audio paths involved assigning the appropriate timeslot to a particular call.
The audio signals were smoothed and integrated by capacitors, giving full response in the telephony band of roughly 300 to 3000 Hz. The 12kHz sampling signal was well above the (intended) bandwidth of the system, but some claimed to hear it, or its effects. Most users, however, heard only the usual crystal-clear analog telephone signals which were expected and typical of telephone systems of that age.
The first production roll-out (that I can find) was at Mayo Clinic in 1963.
It would seem to some that the 101 might be well-suited to CDO (rural Community Dial Office) operation, in a similar architecture to the host-remote scheme commonly seen today. This, unfortunately, was not practical with the 101. If it were, I'm sure that the 101 would have seen a longer and far more visible life. The design of the analog section of the 101 precluded very long loops between the switch and the set. Although off-premises extensions from 101 systems did exist and were somewhat common, the loop length was limited to 10,000 feet or so, and in rural offices, a good percentage of customer loops exceed this threshold. (There's also no evidence that the 101 ever supported party lines of any type, which were still required by the lack of adequate outside plant during the life of the 101.)
There's not that much literature in the public that talks about the nuts and bolts of the 101. The items that are widely available are full of arcane terms such as Stored Program Control, Program Store, Call Store, etc., terms that are not commonly used even by today's hardware-savvy technoids.
Let's talk about some of these.
Stored Program Control means computer control. The system is controlled by a 'stored program engine' which most of us would call a CPU. This CPU was built of discrete components, no microprocessor or VLSI, not even any SSI in the original 101. Computer architects might even call this a very early RISC processor, since the instruction set was small and primitive. However, it had a few very specialized instructions which were well-adapted to the control of the switch.
Program Store is what we would call the executable code, stored in a 1960s era version of what we might call ROM, or Read Only Memory. The ROM memory cards were aluminum-base cards with each bit represented by a magnetized or non-magnetized spot on the card which could be read by the CPU.
Likewise we can think of Call Store, used to store the call information and other items making up the state of the switch, as RAM.
The RAM at the time was ferrite core memory, with each bit being represented by a ferrite bead. The beads were magnetized by a 'write' wire, and the state of each bead was read by a matrix of 'scan' and 'sense' wires.
The 101 could not be re-programmed on the fly in the field. New code sets ('generics') had to be delivered on mag card sets. There were no on-line mass-storage units such as disk drives. These did not come to switching technology until the advent of the 1A ESS many years later.
Many of the features of the 'CPU' of the 101 were adapted to the 1 ESS, but the 1E did not use the TDM switch fabric, instead employing 'fereed' crosspoint switches in crossbar-like configuration.
In Omaha, the 101 Centrex-CU service was promoted heavily beginning in the late 1960s and (at least) two #5 Crossbar offices were adapted to support 101 ESS customers.
The Omaha 101 installations which I can find evidence of are:
Douglas:
Internorth, 348
Clarkson Hospital, 348
Omaha Police, 348
Omaha National Bank, 348
Norwest Bank (now Wells Fargo), 536
Lutheran Hospital, 536
Creighton University, 536
OPPD, 536
UNMC, 536, expanded and cut to 541
Lozier Corporation, 541
This, of course, was the critical mass necessary to make the service practical and profitable to Ma Bell.
Such was not the case in west Omaha.
90th and Western (originally hosted at 135th):
Bergan Mercy Hospital, 398
IBM Corporation, internal PBX, not Centrex, no DID.
Even with the vast westward expansion of Omaha's business community between the 1970s and 1990s, the 101 ESS never saw widespread deployment in the 'burbs', the service being mostly pushed out of the way by 'Centrex CO' services hosted out of 1E and 1A switches.
One of my former employers was 'served' by one of the above 101 installations. My desk phone, for the most part, worked perfectly well as far as regular POTS features, but the custom features such as forwarding, transfer, etc., were sporadic at best.
I know that it worked for 103 type 300bps data calls, not so sure about 1200 and above.
The one quirk which I remember most about the switch was the cadence of the ringdown and ringback. The 101 tone generator used the newer 'precise' sounds for such things as dial tone, ring tone, and busy tone. However, when a call was placed, the first ring was often several times the normal length, then often stuttering before settling in to the normal 1-on, 2-off cadence typical of PBX installations.
I have never received any explanation of why this happened.
I do know that in a later 101 installation in NYC, this quirk was not present, and that 101 had the normal ringback cadence found in other systems.
All 101 installations appeared to have vanished by the mid 1990s or so, mostly replaced by Centrex-CO and Centrex-CU on various Dimension, Definity, and systems of other manufacturers.
An interesting sidebar to the history of the 101 is a legend on the etymology of the term 'octothorpe' to refer to the pound/hash/sharp/whatever sign. It involves the tale of the name being coined on the fly during the commissioning of the Mayo Clinic's Centrex. Researching this will be an exercise for the student. ;-) Hint: Check the archives of Telecom Digest. ;-)
The 101 was Ma Bell's first! Yes, predating the 1E!
Some will tell you that the 101 ESS is essentially the red-headed stepchild of the Bell System. It was quirky, had a short operational life, and had a bad reputation in the field.
For the time, the 101 was ahead of its time, literally. It had many innovations which are reflected in the mature technology of today. It was the first 'stored program control' switching system used in commercial service. (More about that term below.) It was also the first switch to use TDM (Time Division Multiplexing) to switch voice paths. It was Ma Bell's first commercially-deployed switch which supported Touch-Tone
The 101 began life in the 1950s as the EPBX project, Ma Bell's initiative to create a state-of-the-art all-electronic small telephone switch which could be deployed at a customer's premises in lieu of the very bulky, noisy, and space-consuming Step equipment, and the somewhat bulky Crossbar PBX systems.
It was renamed the 101 ESS after the term ESS was settled upon to be the service mark of Ma Bell's electronic switches. The number 101 was chosen since full-scale CO switches were normally assigned single-digit numbers, and PBX systems were normally assigned three-digit numbers. 101 was, of course, the lowest number available under those criteria.
The numbers vary as far as the line capacity of the 101. Some literature will cite limits in the hundreds of lines, others refer to low thousands of lines being available from later 101 systems.
The strategy was to place a large central control unit in the CO, acting as the equivalent of the line link section of an otherwise normal 5 Crossbar office, and a 'smart' remote unit at each customer's premises, connected by an appropriate number of signal and control trunks to the CO. To be commercially viable, each CO supporting 101 service had to serve a certain number of remote customers, 10 or so, depending on size and density.
The 101 service was sold under the service mark of 'Centrex-CU', the CU meaning that (some of) the switching equipment resided at the customer's premises. Centrex-CU included normal features such as direct inward dialing to four-digit extensions, direct outward 'dial 9' service with ANI (automatic calling number identification) with detailed reports and variable billing options, and such 'Custom Calling Features' such as speed dialing, call transfer, camp-on, remote pick-up of a ringing extension, call forwarding, and user-initiated 3-way and 4-way conference calling.
The 101 was also used for some stand-alone, non-DID PBX applications, but these were few and far between.
The technology used at the time for the 101 was discrete-component diode-transistor logic (DTL), making up the bulk of the electronics.
The switch fabric used an innovative but unusual form of analog time division multiplexing. Instead of multiple physical audio paths through the switch matrix, there was one path which was time-shared by all active calls, each being switched in and out at the rate of 12,000 samples per second. The actual 'switching' of audio paths involved assigning the appropriate timeslot to a particular call.
The audio signals were smoothed and integrated by capacitors, giving full response in the telephony band of roughly 300 to 3000 Hz. The 12kHz sampling signal was well above the (intended) bandwidth of the system, but some claimed to hear it, or its effects. Most users, however, heard only the usual crystal-clear analog telephone signals which were expected and typical of telephone systems of that age.
The first production roll-out (that I can find) was at Mayo Clinic in 1963.
It would seem to some that the 101 might be well-suited to CDO (rural Community Dial Office) operation, in a similar architecture to the host-remote scheme commonly seen today. This, unfortunately, was not practical with the 101. If it were, I'm sure that the 101 would have seen a longer and far more visible life. The design of the analog section of the 101 precluded very long loops between the switch and the set. Although off-premises extensions from 101 systems did exist and were somewhat common, the loop length was limited to 10,000 feet or so, and in rural offices, a good percentage of customer loops exceed this threshold. (There's also no evidence that the 101 ever supported party lines of any type, which were still required by the lack of adequate outside plant during the life of the 101.)
There's not that much literature in the public that talks about the nuts and bolts of the 101. The items that are widely available are full of arcane terms such as Stored Program Control, Program Store, Call Store, etc., terms that are not commonly used even by today's hardware-savvy technoids.
Let's talk about some of these.
Stored Program Control means computer control. The system is controlled by a 'stored program engine' which most of us would call a CPU. This CPU was built of discrete components, no microprocessor or VLSI, not even any SSI in the original 101. Computer architects might even call this a very early RISC processor, since the instruction set was small and primitive. However, it had a few very specialized instructions which were well-adapted to the control of the switch.
Program Store is what we would call the executable code, stored in a 1960s era version of what we might call ROM, or Read Only Memory. The ROM memory cards were aluminum-base cards with each bit represented by a magnetized or non-magnetized spot on the card which could be read by the CPU.
Likewise we can think of Call Store, used to store the call information and other items making up the state of the switch, as RAM.
The RAM at the time was ferrite core memory, with each bit being represented by a ferrite bead. The beads were magnetized by a 'write' wire, and the state of each bead was read by a matrix of 'scan' and 'sense' wires.
The 101 could not be re-programmed on the fly in the field. New code sets ('generics') had to be delivered on mag card sets. There were no on-line mass-storage units such as disk drives. These did not come to switching technology until the advent of the 1A ESS many years later.
Many of the features of the 'CPU' of the 101 were adapted to the 1 ESS, but the 1E did not use the TDM switch fabric, instead employing 'fereed' crosspoint switches in crossbar-like configuration.
In Omaha, the 101 Centrex-CU service was promoted heavily beginning in the late 1960s and (at least) two #5 Crossbar offices were adapted to support 101 ESS customers.
The Omaha 101 installations which I can find evidence of are:
Douglas:
Internorth, 348
Clarkson Hospital, 348
Omaha Police, 348
Omaha National Bank, 348
Norwest Bank (now Wells Fargo), 536
Lutheran Hospital, 536
Creighton University, 536
OPPD, 536
UNMC, 536, expanded and cut to 541
Lozier Corporation, 541
This, of course, was the critical mass necessary to make the service practical and profitable to Ma Bell.
Such was not the case in west Omaha.
90th and Western (originally hosted at 135th):
Bergan Mercy Hospital, 398
IBM Corporation, internal PBX, not Centrex, no DID.
Even with the vast westward expansion of Omaha's business community between the 1970s and 1990s, the 101 ESS never saw widespread deployment in the 'burbs', the service being mostly pushed out of the way by 'Centrex CO' services hosted out of 1E and 1A switches.
One of my former employers was 'served' by one of the above 101 installations. My desk phone, for the most part, worked perfectly well as far as regular POTS features, but the custom features such as forwarding, transfer, etc., were sporadic at best.
I know that it worked for 103 type 300bps data calls, not so sure about 1200 and above.
The one quirk which I remember most about the switch was the cadence of the ringdown and ringback. The 101 tone generator used the newer 'precise' sounds for such things as dial tone, ring tone, and busy tone. However, when a call was placed, the first ring was often several times the normal length, then often stuttering before settling in to the normal 1-on, 2-off cadence typical of PBX installations.
I have never received any explanation of why this happened.
I do know that in a later 101 installation in NYC, this quirk was not present, and that 101 had the normal ringback cadence found in other systems.
All 101 installations appeared to have vanished by the mid 1990s or so, mostly replaced by Centrex-CO and Centrex-CU on various Dimension, Definity, and systems of other manufacturers.
An interesting sidebar to the history of the 101 is a legend on the etymology of the term 'octothorpe' to refer to the pound/hash/sharp/whatever sign. It involves the tale of the name being coined on the fly during the commissioning of the Mayo Clinic's Centrex. Researching this will be an exercise for the student. ;-) Hint: Check the archives of Telecom Digest. ;-)
Friday, February 19, 2010
So, how does a panel office work ??
The Panel Office
This will describe the basic components of the typical panel central office. In our next installment, we'll trace a call through a panel office, showing exactly what happens in each stage of the process. We'll also describe the 'revertive pulsing', the method by which panel offices communicate with eac other, in some depth in a subsequent article.
I've been fascinated with the panel offices ever since being served by one and discovering some of its quirks. In the 1970s I was actually able to schmooze my way in for a late-night off-the-record tour of one, which only increased my interest.
In the 1970s, the panel switch was the Rodney Dangerfield of telecom. It got no respect! It was considered to be crufty, unreliable, low-tech, old, antiquated, a Rube Goldberg machine, and the like.
For the 1920s, however, the panel switch was high-tech. It was bleeding-edge for its time. In those days the practicality of providing machine-switched telephone service to large metropolitan areas was unproven, and the Panel installation in Omaha, beginning in 1921, was the proof of concept.
The term 'panel' comes from the panels of contacts which make up the frames which comprise a panel switching office. Each 'frame' consists of a panel of contacts, arranged normally in 5 banks of 100 contacts each, or in 10 banks of 40 contacts each for the (newer) linefinder frames. Each frame has 60 selector rods, 30 on the front, 30 on the rear, with each rod having normally 5 contact 'brushes', with the rods on the linefinder frames having 10 contact brushes.
The selector rods are positioned over the correct contacts on the panels by motor-driven cork rollers located toward the bottom of the frames. Clutches for up-drive, down-drive (and slow up-drive on the final frame) control the movement of the selector rods.
The brushes are the movable contacts which connect to the fixed contacts upon the banks of the panel switch.
Let's take a quick overview of what comprises (or comprised, this is all in the past tense here, actually) the typical real-world panel office and discuss the various parts.
In the diagram above we show the various frames of the panel office, plus some of the major ancillary components.
Five types of panel switching frames existed, with four of them appearing in all full-blown panel offices and a fifth type existing in those in the largest metropolitan areas.
Besides the actual switching frames, other important parts of the panel office included:
This is a basic overview of a typical panel central office. In the next installment we'll show the progress of a call from receiver off hook to receiver off hook as it works its way through the panel switches.
This will describe the basic components of the typical panel central office. In our next installment, we'll trace a call through a panel office, showing exactly what happens in each stage of the process. We'll also describe the 'revertive pulsing', the method by which panel offices communicate with eac other, in some depth in a subsequent article.
I've been fascinated with the panel offices ever since being served by one and discovering some of its quirks. In the 1970s I was actually able to schmooze my way in for a late-night off-the-record tour of one, which only increased my interest.
In the 1970s, the panel switch was the Rodney Dangerfield of telecom. It got no respect! It was considered to be crufty, unreliable, low-tech, old, antiquated, a Rube Goldberg machine, and the like.
For the 1920s, however, the panel switch was high-tech. It was bleeding-edge for its time. In those days the practicality of providing machine-switched telephone service to large metropolitan areas was unproven, and the Panel installation in Omaha, beginning in 1921, was the proof of concept.
The term 'panel' comes from the panels of contacts which make up the frames which comprise a panel switching office. Each 'frame' consists of a panel of contacts, arranged normally in 5 banks of 100 contacts each, or in 10 banks of 40 contacts each for the (newer) linefinder frames. Each frame has 60 selector rods, 30 on the front, 30 on the rear, with each rod having normally 5 contact 'brushes', with the rods on the linefinder frames having 10 contact brushes.
The selector rods are positioned over the correct contacts on the panels by motor-driven cork rollers located toward the bottom of the frames. Clutches for up-drive, down-drive (and slow up-drive on the final frame) control the movement of the selector rods.
The brushes are the movable contacts which connect to the fixed contacts upon the banks of the panel switch.
Let's take a quick overview of what comprises (or comprised, this is all in the past tense here, actually) the typical real-world panel office and discuss the various parts.
In the diagram above we show the various frames of the panel office, plus some of the major ancillary components.
Five types of panel switching frames existed, with four of them appearing in all full-blown panel offices and a fifth type existing in those in the largest metropolitan areas.
- Linefinder frames
A complete full-scale panel office will have 25 linefinder frames, each serving a group of 400 subscriber lines, for a total of 10,000 lines. (Researching the proverbial 10,500 line panel offices will be an exercise for the student.)
The linefinder frame provides the connection to the subscriber's telephone set when the receiver is taken off hook, and routes that connection first to the register-sender and then to a corresponding district frame. - District frames
District selector frames appear in all panel offices. In panel offices in smaller communities (ya know, it's difficult for me to write all of this in the past tense, so if you don't mind, I'll do this in the present tense as if these things still exist today, ok?) the district selector frames provide the outgoing connection from the subscriber, via the linefinder, to either inter-office trunks to other central offices, or intra-office trunks to incoming frames in the same central office.
Each district frame can connect to 500 trunks, so there is a practical limit, and in larger communities a second stage of outgoing selectors is provided. - Office frames
In the largest communities where there are many central offices, 500 outgoing trunks from a panel office is inadequate, so a second stage of outgoing selection is provided by 'office' frames. These frames only appeared (there I go mixing tenses again) in the largest metropolitan areas, such as New York City, Chicago, etc. It's believed that Omaha's panel offices used only the district frames for the outgoing connections.
The district and office frames select the particular central office of the call to be completed. - Incoming frames
The incoming frame of a panel office is the first stage of selection of the called station. The incoming frame connects the incoming inter-office or intra-office trunk to the particular final frame which serves the called subscriber.
The incoming frame consists of five banks, each with 100 contacts. Each bank is served by one brush on each of the selector rods. This allows a maximum of 25 connections between the incoming frame and the final frame. These sets of 25 connections are referred to as a 'group', and there are four groups within each bank, for a total of 20 groups within the incoming frame. - Final frames
Each final frame can serve 500 subscribers, therefore there will be 20 final frames in a complete panel office serving 10,000 subscriber lines. The final frame connects the incoming call to the subscriber's station, and provides the logic to test for line busy, to supply ringing voltage to the called line, to return the ringback tone (or busy tone) to the calling subscriber, and to remove ringdown/ringback and complete the talking path when the called subscriber answers.
Besides the actual switching frames, other important parts of the panel office included:
- The Register-Sender. (Sometimes called just 'sender'.)
Think of this as the 'brain' or the 'CPU' of the panel office. It's actually a collection of electromechanical relay-logic circuitry. This is the main 'Common Control' section of the panel office. The register-sender records the digits dialed by the calling subscriber and gives the commands to the various frames, both in the originating office and the terminating office, as to how to position the brushes against the banks of contacts, in order to complete the call.
The register-sender is only needed at the initial call set-up phase. It is dismissed once the selector rods are all in place and the call is in the ringing or the line-busy state.
A full-scale panel office would have anywhere between 3 and 6 or so register-senders depending on the volume of calls anticipated. - The Translator or Decoder.
While the positions of the selectors on the incoming and final frames are easily determined by the called subscriber's number, the connections to various intra and inter-office trunks are quite arbitrary and vary considerably from community to community.
The register-sender calls upon the Translator (earlier panel offices) or Decoder (later panel offices) to determine how to route the call through the district frame and, if used, the office frame. - The Sender-Link circuitry.
Each connection between the linefinder frame and the district frame has a set of multi-contact relays and associated circuitry which allows it to 'seize' an idle register sender when the subscriber goes off hook.
Note that the register-sender is only needed for a few seconds for each call. It receives the digits, does some lookups via the translator/decoder, sets up the call, and is then available for another call.
'Slow dial tone' on a panel office is almost always due to the fact that all register-senders are busy at the time. - The Tone Plant.
In the typical panel office, this is a rotary electromechanical device about the size of and in some ways resembling a metal lathe. This contains rotary generators for the low-voltage tones which make up dial tone, busy tone, etc., and the high-voltage (90-100 v 20Hz) ringing signal.
Interrupters are driven by a step-down gear train. These provide the cadences for such things as ringdown, ringback, busy tone, etc. Some of these would use a rotary brush arrangement, while others used mercury-filled rotating drums to interrupt the signals.
The various tones and signals which come from the tone plant are:- Dial tone. This would be the older non-precise dial tone for panel offices not converted for touch-tone service.
- Busy tone. This would be the older somewhat rude and raucous 'BAWW BAWW BAWW BAWW' tone, interrupted at 60 impulses per minute, returned to the calling subscriber for a line busy condition. Even panel offices which were converted to touch-tone retained this tone for busy-back.
- Ringback tone. For most panel offices this would be the non-precise 'metropolitan ring' tone, electromechanically generated and interrupted normally with a [corrected] two seconds on, four seconds off cadence.
- Reorder tone. Same as the busy tone, but interrupted at 120 impulses per minute. 'Fast busy'. Used for various all trunks/circuits/equipment busy conditions.
- No such number or 'vacant code' tone. A deprecated intermittent fast busy type tone used to indicate numbers, prefixes, etc., which did not exist. This was phased out as recorded 'The number you have reached is not in service' announcements were phased in.
- Permanent signal, or 'receiver off hook' tone. No, this was not the very loud and obnoxious 'CLANK CLANK CLANK' receiver off hook sound of today. It was a single high-pitched tone, returned to the calling subscriber when the register sender got tired of waiting for dialed digits and routed the call to be 'parked' on a 'permanent signal trunk' on the district frame.
- Dial tone. This would be the older non-precise dial tone for panel offices not converted for touch-tone service.
- The Intra-Office trunks.
From the perspective of the register-sender, a call within the local central office is identical to that going to a remote central office, or to another panel office within the same building. Each panel office would have a certain amount of hard-wired connections reserved for intra-office calls, connected between the local office (or district) frames and local incoming frames. - The Inter-Office trunks.
These were the outgoing and incoming connections to and from distant central offices. In the early days of panel offices, these were simply loaded two-wire circuits with a frequency response of DC through 3kHz or so. When setting up a call to a distant panel central office, it was the register-sender of the originating CO which controlled the operation of the incoming and final frames in the terminating CO. - The batteries and power plant (not shown).
Primary central office power is provided by huge lead-acid cells, which are continuously charged by motor-generator sets (MGs) or rotary converters. This is very typical of central offices today, except that solid-state rectifiers now replace the former electromechanical devices. In the heyday of panel offices, commercial power was normally used to run the MGs or converters, supplanted by on-site diesel, gasoline, or LP generators to be used for commercial power outages.
This is a basic overview of a typical panel central office. In the next installment we'll show the progress of a call from receiver off hook to receiver off hook as it works its way through the panel switches.
Saturday, January 30, 2010
Updates
Thanks to those who sent in updates, additional information, and corrections.
These can be sent in either via e-mail or as comments.
Two updates of some significance have been reported.
Thanks, gang, and keep those cards and letters coming.
These can be sent in either via e-mail or as comments.
Two updates of some significance have been reported.
- A recently-retired long-time TPC employee has stated that in his recollection the Elkhorn and Waterloo CDOs were separate, discrete, and each located in their respective towns prior to 289 and 779 going ESS in the mid 1970s. I do recall that at one time prior to the cut, the same numbers could be dialed using either prefix. We may have to agree to disagree on this factoid until something in writing can be located.
- A person 'in the know' reports that the Internorth Centrex on 633 was Centrex-CU using a local WECO Definity, as opposed to a Centrex-CO hosted off of the main switch as I had erroneously reported.
- Late update: Another former TPCer reports that Council Bluffs did not use the Omaha time announcement service on 844-8111 and the 844 prefix was not dialable from Council Bluffs. Instead they had their own similar time announcement machine on 328-8116. This time announcement machine could also be reached from Glenwood, which at the time was not within the Council Bluffs calling area.
Thanks, gang, and keep those cards and letters coming.
Sunday, January 17, 2010
The CDO's
Historically speaking, in the 1950s and 1960s the small towns surrounding Omaha in Douglas and Sarpy counties had local dial service, but very limited local calling areas. These communities were served by 'Community Dial Offices' consisting of smaller direct-control Step-By-Step (Strowger) facilities. These typically served anywhere from a few hundred to a few thousand subscribers.
The switches in these offices were typically configured to allow 'permissive' 5 or 7 digit dialing. For a call within the office, the full seven-digit number could be dialed, but only the last five digits were actually required. 'Digit absorbing' first selectors in these offices permitted dialing plans such as this.
Party lines were very common in these offices until the 1970s, with the far rural areas having availability of four-party fully-selective service (ringer is silent except for calls to that particular subscriber) if they were lucky, but often times eight-party semi-selective (one long ring or two short) service only.
Ma Bell chose to avoid the frequency-selective ringers used by independent telcos which allowed fully-selective ringing for up to 12 parties on a single line. Instead they chose a system where the ringing voltage was applied to either one conductor or the other, in either a positive or negative polarity, giving four possible fully-selective combinations. To service eight parties, one-long and two-short ringer cadences were used.
The advent of Subscriber Carrier ('AML') in the late 1960s provided some relief for far rural subscribers, but the result was often that one lucky subscriber on each rural line received a private line, while all others were stuck with eight-party semi-selective service.
Bare copper open-wire lines, supported on wooden crossarms with glass insulators were still in use into the 1970s. As these were upgraded to either multi-conductor aerial or underground lines, the availability of single-party private lines became common in rural areas.
Around 1970, several nearby communities with existing CDO's were integrated into Omaha's toll-free local calling area. This made significant use of the 19th. St. Crossbar Tandem office. As phone 'enthusiasts' know, Step offices do not easily interface directly with Panel and some #1 Crossbar offices, making either a tandem office or a toll office a necessity to provide direct dial service between them.
Calls from metropolitan Omaha to these extended-area offices required the usual seven digits, and except in a very few cases, these calls were routed through the Crossbar Tandem. The outpulsing of dial pulses from the Crossbar Tandem to the Step CDO was clearly audible after dialing was finished.
Calls from these CDO's to Omaha numbers or other CDO's required the dialing of an access code, usually 5 or 7, in addition to the seven-digit number. The dialing of this access code caused the first selector in the CDO to seize a trunk to the downtown Tandem's dial-pulse receiver.
One-plus Direct Distance Dialing from these offices was available, but DDD calls were routed to a 'CAMA Intercept' operator to verify and record the calling number, since automatic number identification of the calling number was not possible with the Step type CDO equipment.
Trunking from the Tandem to the CDOs at the time used analog medium-haul trunks with hissy analog repeaters, and background noise and 'singing' on calls to and between these offices was not uncommon.
In the mid 1970s, these offices were converted one by one to smaller WECO ESS units, but it most cases the calls were still routed via the 19th. St. Tandem.
Although calls to metropolitan Omaha (including Carter Lake) were toll-free, calls to Council Bluffs were long-distance to and from these communities until the 1990s.
All of these CDO's were converted to ESS in the mid 1970s, allowing for Touch-Tone and various calling features, but toll-free calling to and from Council Bluffs would not come for another two decades.
The switches in these offices were typically configured to allow 'permissive' 5 or 7 digit dialing. For a call within the office, the full seven-digit number could be dialed, but only the last five digits were actually required. 'Digit absorbing' first selectors in these offices permitted dialing plans such as this.
Party lines were very common in these offices until the 1970s, with the far rural areas having availability of four-party fully-selective service (ringer is silent except for calls to that particular subscriber) if they were lucky, but often times eight-party semi-selective (one long ring or two short) service only.
Ma Bell chose to avoid the frequency-selective ringers used by independent telcos which allowed fully-selective ringing for up to 12 parties on a single line. Instead they chose a system where the ringing voltage was applied to either one conductor or the other, in either a positive or negative polarity, giving four possible fully-selective combinations. To service eight parties, one-long and two-short ringer cadences were used.
The advent of Subscriber Carrier ('AML') in the late 1960s provided some relief for far rural subscribers, but the result was often that one lucky subscriber on each rural line received a private line, while all others were stuck with eight-party semi-selective service.
Bare copper open-wire lines, supported on wooden crossarms with glass insulators were still in use into the 1970s. As these were upgraded to either multi-conductor aerial or underground lines, the availability of single-party private lines became common in rural areas.
Around 1970, several nearby communities with existing CDO's were integrated into Omaha's toll-free local calling area. This made significant use of the 19th. St. Crossbar Tandem office. As phone 'enthusiasts' know, Step offices do not easily interface directly with Panel and some #1 Crossbar offices, making either a tandem office or a toll office a necessity to provide direct dial service between them.
Calls from metropolitan Omaha to these extended-area offices required the usual seven digits, and except in a very few cases, these calls were routed through the Crossbar Tandem. The outpulsing of dial pulses from the Crossbar Tandem to the Step CDO was clearly audible after dialing was finished.
Calls from these CDO's to Omaha numbers or other CDO's required the dialing of an access code, usually 5 or 7, in addition to the seven-digit number. The dialing of this access code caused the first selector in the CDO to seize a trunk to the downtown Tandem's dial-pulse receiver.
One-plus Direct Distance Dialing from these offices was available, but DDD calls were routed to a 'CAMA Intercept' operator to verify and record the calling number, since automatic number identification of the calling number was not possible with the Step type CDO equipment.
Trunking from the Tandem to the CDOs at the time used analog medium-haul trunks with hissy analog repeaters, and background noise and 'singing' on calls to and between these offices was not uncommon.
In the mid 1970s, these offices were converted one by one to smaller WECO ESS units, but it most cases the calls were still routed via the 19th. St. Tandem.
Although calls to metropolitan Omaha (including Carter Lake) were toll-free, calls to Council Bluffs were long-distance to and from these communities until the 1990s.
- Elkhorn and Waterloo
Originally, Elkhorn and Waterloo, neighboring communities separated by the Elkhorn River, each had their own local Step CDO. These were combined just prior to the extended calling area, resulting in the Elkhorn office serving both the 289 and 779 prefixes.
An access code of 5 was required to dial numbers other than Elkhorn or Waterloo.
Although residents of Elkhorn continued to be assigned 289 numbers, and residents of Waterloo continued to be assigned 779 numbers, the prefix codes were interchangeable and 'aliased' to each other as long as the office remained on the Step equipment.
Due to the aliasing, the digit absorbtion, and the tandem connection, a local call from a 289/779 number to another could be dialed with 9 plus the last four digits, either 289 or 779 and the last four digits, or 5 plus either 289 or 779 and the last four digits.
The Elkhorn CDO was cut to a #2 ESS around 1975. Some subscribers expressed dismay at losing the 5-digit 'shortcut' for Elkhorn and Waterloo calls. At this time 289 and 779 became discrete offices. - Bennington
The Bennington CDO had a very large service area but only a few hundred subscribers in the Step CDO days, including the town of Elk City, and extending as far north as some parts of Washington County, including the unincorporated community of Washington.
Only two levels of the 238 prefix were actually in service, with the 9000 level aliased to the 2000 level, allowing for only 1000 total lines.
It was rumored, but not substantiated, that Ma Bell put the Bennington CO and facilities up for sale to another telco during the 1990s.
An access code of 7 was required for calls to other communities. - Valley
The Valley CDO was the most northwest in Douglas County, but the service area extended far south to the communities of Two Rivers and Venice.
Several auto dealers in Fremont subscribed to FX service out of Valley to provide flat-rate toll-free service from Omaha customers, prior to the inclusion of Fremont in the Omaha toll-free calling area.
The Valley CDO hosted the 359 prefix.
An access code of 7 was required for calls to other offices. - Springfield
Springfield was the smallest of the CDOs with only the 2000 and 9000 levels provisioned, again aliased to each other. An access code of 7 was required for calls to other offices.
A somewhat controversial decision by the Ma Bell powers that be was to cable the upstart community of Hawaiian Village, literally a stone's throw away from Springfield, to the far-more-distant 84th. and Harrison office.
The Springfield CDO hosted the 253 prefix. - Gretna
The Gretna CDO had the distinction of hosting the most distant local calls from metropolitan Omaha, those being in the Linoma Beach and Beaconview communities, halfway between downtown Omaha and Lincoln.
During the Step days, an access code of 7 was required for calls to other offices.
The Gretna office hosted the 332 prefix. Due the similarity of 332 to other west Omaha prefixes, this was sometimes perceived as being 'more urban' than the other CDO's.
All of these CDO's were converted to ESS in the mid 1970s, allowing for Touch-Tone and various calling features, but toll-free calling to and from Council Bluffs would not come for another two decades.
Saturday, January 16, 2010
The Expansions - The New Prefixes
Omaha's growth and increased telecom usage sparked the equipment upgrades and addition of the following prefixes to existing COs between our timeline start in 1953 and our checkpoint of 1977.
Douglas:
In the mid 1950s, a new #5 Crossbar system was installed at 19th. and Douglas, replacing much of the aging Panel installation, part of which was Ma Bell's first Panel roll-out, serving ATlantic and JAckson. The first new prefix was EXpress, originally serving as Ma Bell's own internal Centrex. EXpress (and later 344) served some of the very first IMTS (direct-dial) mobile phones.
A recorded time service was launched out of the Douglas Crossbar with a listed number of TIme-8111. See further notes on 844 below.
At the time of the Great Renumbering 348 was added to the 19th. St. #5 Crossbar, becoming Omaha's first prefix not to have descended from a legacy named exchange. There is some evidence that what became the 348 prefix was originally scheduled to be launched prior to the Great Renumbering (tentative name of BLackstone), but that various circumstances delayed the roll-out until September of 1960.
At the same time, 347, serving Carter Lake, was added to the Crossbar, giving Carter Lake its own dedicated prefix. See separate article for more details on this.
271 and 281 were an enigmatic pair of prefixes, and elicited hours upon hours of talk, experimentation, and speculation among telephone 'afficianados'. :) These served the Union Pacific Headquarters exclusively at the time. Whether the UP installation was Centrex or DID-PBX is really a question of semantics. It was basically an on-premesis Step installation driven by the #5 Crossbar at 19th. and Douglas.
The only listed number on the 281 prefix was the main UP incoming number, 281-5822. All other listed numbers for UP were on 271. The two prefixes 271 and 281 were 'aliased' to each other and could be interchangably dialed. You could dial either prefix plus the last four digits. Consensus was that this was done to 'balance the load' somewhat, directing the calls to the main number over one set of trunks, and direct-dialed calls to various UP offices to another.
221 was another Centrex-or-DID-PBX which served the Federal offices in Omaha. Again, a Step installation off of the #5 Crossbar.
536 and 541 were set up on the #5 Crossbar to serve mainly 101 ESS Centrex-Cu customers, some of which were also served by 348. Original Centrex-CU customers out of these offices were Norwest Bank, Lutheran Hospital, UNMC, and Lozier Corporation, among others.
Phone 'enthusiasts' were quick to note that of these new prefixes, access to 536 from many other Omaha offices was via the downtown Crossbar Tandem, and a distinctive burst of MF could often be heard when calls to 536 were placed.
The big addition to the 19th. and Douglas office was a very significant #1 ESS, commissioned around 1970. This replaced the last of the Panel (345, 346) and added 422, 444, 449, and eventually 633, 636, 977, and 978, among countless others as the facilities were expanded..
Ma Bell's internal Centrex was then converted to 422 on the ESS, and Centrex-CO for Eppley Airfield was added to 422 as well.
The main customer on 444 was the Douglas County offices, including County Hospital, a Centrex-CO installation. 444 also served some IMTS mobile phone customers.
The then-new St. Joseph hospital on north 30th. was the first major customer on 449, Centrex-CO.
633, 636, 977, and 978 were added during an expansion in the late 1970s, mostly intended to serve large Centrex-CO customers. OPPD, originally a Centrex-CU customer on 536, eventually spilled over to 636 as well. InterNorth (nee' Northern Natural Gas) was the first major customer on 633, a Centrex-CO replacing the former #101 Centrex-CU on 348. Omaha Public Schools was the first major customer on 978. 977 was at first mainly used for pagers and some pre-cellular mobile phones.
844 was hosted out of Douglas, used exclusively for the automated 'Time' service. 844-8111 was the published number, but anyone with any kind of curiosity knew that the time recording could be reached equally well by dialing 844 and any four random digits.
No, I haven't forgotten about 894. Yes, at the turn of the 21st. Century, 894 is a general service prefix out of 156th. and Harrison. However, 894 began life as a somewhat red-headed-stepchild 'choke' prefix out of Douglas.
Only two published numbers ever appeared on the orignal 894 prefix, one being a recorded weather announcement, sponsored by a radio station, and another a medical advice recording, sponsored by a local hospital.
894 was originally hosted on the #5 crossbar, as an 'alias' for 344. You could dial either 344 or 894 plus the four digits and get the same number.
However, when the #1 ESS came to life, shortly after the 894 prefix was moved to ESS and 'aliased' to 444.
341, 342, 344, 347, 348, 536, and 541 remained on the #5 Crossbar well into the 1980s.
So, at our 1977 checkpoint, we have the following out of Douglas Street:
221, 271, 281, 341, 342, 344, 345, 346, 347, 348, 422, 444, 449, 536, 541, 633, 636, 844, 894, 977, and 978.
Izard:
The Panel office serving 551 and 553 remained in service well into the 1970s, until a new #1 ESS replaced it. Along with 551 and 553, 554 and 559 were added to the new #1 ESS.
556 and 558 remained on the #1 Crossbar into the 1980s.
An interesting quirk was that while the Izard #1 ESS was being installed, what would become the 551 and 553 sections were temporarily accessible from several other Omaha offices via 531 and 533. Many phone 'afficianados' became 'acquainted' with the Izard ESS this way.
'Bay 1, circuit 2, Centrex Direct Inward Dialing intercept.' :)
1977 checkpoint prefixes were: 551, 553, 554, 556, 558, and 559.
Fowler:
KEnwood was the last remaining Omaha office to have manual ('Numberrr Pleeze') service. KEnwood was added to the Fowler #1 Crossbar in about 1957, finally bringing dial service to all of Omaha. 457 was added as an expansion in the late 1960s.
Prefixes as of the checkpoint: 451, 453, 455, and 457.
O Street:
The only major expansion to the long-lived O Street #1 Crossbar was the addition of the 734 prefix around 1970. O street was the only one of Omaha's #1 Crossbar offices which was converted to MF signaling on the interoffice trunks. The others (Izard, Fowler) used revertive pulsing throughout their lives.
The O Street #1 Crossbar lived on until around 1985.
1979 prefixes: 731, 733, 734.
Bellevue:
I admit. I don't really know too much about the Bellevue CO. The earliest I remember this CO was in the early 1970s, and it was a #5 Crossbar. It was a bit quirky in that it had a tone plant which gave a ringback tone which could best be described as a 'low rumble', with not very much in the way of tones or harmonics as were typical in the 'metropolitan' ringing machines which were common on Panel, #1, and #5 Crossbar offices, or the newer 'precise' tones.
The nuances of the connections indicated that it was most definitely a #5 Crossbar.
At the time of the Great Renumbering, the only prefix in Bellevue was 291. 292 and 293 were added in the early and late 1970s respectively as the community expanded.
I'm not really sure if the 294 prefix, which served Offutt Air Force Base exclusively at the time, was actually hosted out of Bellevue, or out of Douglas. I've heard some 'in the know' people say one, and some say the other.
Prefixes at the 1977 checkpoint: 291, 292, 293. Honorable mention: 294.
Council Bluffs:
The area's first #1 ESS switch was installed in Council Bluffs ca. 1970, replacing the Step offices serving 322 and 323. An additional prefix, 328, was added at the time of the cut, and 325 followed several years after, giving the main Council Bluffs downtown CO a total of four prefixes at the time of our checkpoint.
In 1971, toll-free direct seven-digit dialing was established between Council Bluffs and metropolitan Omaha.
Along with metropolitan Council Bluffs, the Manawa CO, serving prefix 366, was added to the Omaha dialing area. The Manawa office was unique in that it used 'directorized' Step switches. This was a typical up-and-around Strowger-switch type office, but with a common-control 'Director' device added. The Director was between the linefinder and the first selector. The Director returned dial tone to the subscriber, received the dialed digits, and then drove the switches appropriately to set up either an intra-office or inter-office call. This also allowed true Touch-Tone service on this Step office, as opposed to a simple tone to pulse converter. The Manawa office was the only Director Step office in the Omaha area.
Council Bluffs also had toll-free calling to a few nearby rural CDO's, all on the Iowa side, in Silver City/Mineola (526), Crescent (545), and Underwood (566), but these remained toll calls from Omaha (and Carter Lake, Iowa) until the 1980s.
Prefixes as of the 1977 checkpoint: 322, 323, 325, 328 downtown CB and 366 in Manawa.
In the mid 1950s, a new #5 Crossbar system was installed at 19th. and Douglas, replacing much of the aging Panel installation, part of which was Ma Bell's first Panel roll-out, serving ATlantic and JAckson. The first new prefix was EXpress, originally serving as Ma Bell's own internal Centrex. EXpress (and later 344) served some of the very first IMTS (direct-dial) mobile phones.
A recorded time service was launched out of the Douglas Crossbar with a listed number of TIme-8111. See further notes on 844 below.
At the time of the Great Renumbering 348 was added to the 19th. St. #5 Crossbar, becoming Omaha's first prefix not to have descended from a legacy named exchange. There is some evidence that what became the 348 prefix was originally scheduled to be launched prior to the Great Renumbering (tentative name of BLackstone), but that various circumstances delayed the roll-out until September of 1960.
At the same time, 347, serving Carter Lake, was added to the Crossbar, giving Carter Lake its own dedicated prefix. See separate article for more details on this.
271 and 281 were an enigmatic pair of prefixes, and elicited hours upon hours of talk, experimentation, and speculation among telephone 'afficianados'. :) These served the Union Pacific Headquarters exclusively at the time. Whether the UP installation was Centrex or DID-PBX is really a question of semantics. It was basically an on-premesis Step installation driven by the #5 Crossbar at 19th. and Douglas.
The only listed number on the 281 prefix was the main UP incoming number, 281-5822. All other listed numbers for UP were on 271. The two prefixes 271 and 281 were 'aliased' to each other and could be interchangably dialed. You could dial either prefix plus the last four digits. Consensus was that this was done to 'balance the load' somewhat, directing the calls to the main number over one set of trunks, and direct-dialed calls to various UP offices to another.
221 was another Centrex-or-DID-PBX which served the Federal offices in Omaha. Again, a Step installation off of the #5 Crossbar.
536 and 541 were set up on the #5 Crossbar to serve mainly 101 ESS Centrex-Cu customers, some of which were also served by 348. Original Centrex-CU customers out of these offices were Norwest Bank, Lutheran Hospital, UNMC, and Lozier Corporation, among others.
Phone 'enthusiasts' were quick to note that of these new prefixes, access to 536 from many other Omaha offices was via the downtown Crossbar Tandem, and a distinctive burst of MF could often be heard when calls to 536 were placed.
The big addition to the 19th. and Douglas office was a very significant #1 ESS, commissioned around 1970. This replaced the last of the Panel (345, 346) and added 422, 444, 449, and eventually 633, 636, 977, and 978, among countless others as the facilities were expanded..
Ma Bell's internal Centrex was then converted to 422 on the ESS, and Centrex-CO for Eppley Airfield was added to 422 as well.
The main customer on 444 was the Douglas County offices, including County Hospital, a Centrex-CO installation. 444 also served some IMTS mobile phone customers.
The then-new St. Joseph hospital on north 30th. was the first major customer on 449, Centrex-CO.
633, 636, 977, and 978 were added during an expansion in the late 1970s, mostly intended to serve large Centrex-CO customers. OPPD, originally a Centrex-CU customer on 536, eventually spilled over to 636 as well. InterNorth (nee' Northern Natural Gas) was the first major customer on 633, a Centrex-CO replacing the former #101 Centrex-CU on 348. Omaha Public Schools was the first major customer on 978. 977 was at first mainly used for pagers and some pre-cellular mobile phones.
844 was hosted out of Douglas, used exclusively for the automated 'Time' service. 844-8111 was the published number, but anyone with any kind of curiosity knew that the time recording could be reached equally well by dialing 844 and any four random digits.
No, I haven't forgotten about 894. Yes, at the turn of the 21st. Century, 894 is a general service prefix out of 156th. and Harrison. However, 894 began life as a somewhat red-headed-stepchild 'choke' prefix out of Douglas.
Only two published numbers ever appeared on the orignal 894 prefix, one being a recorded weather announcement, sponsored by a radio station, and another a medical advice recording, sponsored by a local hospital.
894 was originally hosted on the #5 crossbar, as an 'alias' for 344. You could dial either 344 or 894 plus the four digits and get the same number.
However, when the #1 ESS came to life, shortly after the 894 prefix was moved to ESS and 'aliased' to 444.
341, 342, 344, 347, 348, 536, and 541 remained on the #5 Crossbar well into the 1980s.
So, at our 1977 checkpoint, we have the following out of Douglas Street:
221, 271, 281, 341, 342, 344, 345, 346, 347, 348, 422, 444, 449, 536, 541, 633, 636, 844, 894, 977, and 978.
The Panel office serving 551 and 553 remained in service well into the 1970s, until a new #1 ESS replaced it. Along with 551 and 553, 554 and 559 were added to the new #1 ESS.
556 and 558 remained on the #1 Crossbar into the 1980s.
An interesting quirk was that while the Izard #1 ESS was being installed, what would become the 551 and 553 sections were temporarily accessible from several other Omaha offices via 531 and 533. Many phone 'afficianados' became 'acquainted' with the Izard ESS this way.
'Bay 1, circuit 2, Centrex Direct Inward Dialing intercept.' :)
1977 checkpoint prefixes were: 551, 553, 554, 556, 558, and 559.
KEnwood was the last remaining Omaha office to have manual ('Numberrr Pleeze') service. KEnwood was added to the Fowler #1 Crossbar in about 1957, finally bringing dial service to all of Omaha. 457 was added as an expansion in the late 1960s.
Prefixes as of the checkpoint: 451, 453, 455, and 457.
The only major expansion to the long-lived O Street #1 Crossbar was the addition of the 734 prefix around 1970. O street was the only one of Omaha's #1 Crossbar offices which was converted to MF signaling on the interoffice trunks. The others (Izard, Fowler) used revertive pulsing throughout their lives.
The O Street #1 Crossbar lived on until around 1985.
1979 prefixes: 731, 733, 734.
I admit. I don't really know too much about the Bellevue CO. The earliest I remember this CO was in the early 1970s, and it was a #5 Crossbar. It was a bit quirky in that it had a tone plant which gave a ringback tone which could best be described as a 'low rumble', with not very much in the way of tones or harmonics as were typical in the 'metropolitan' ringing machines which were common on Panel, #1, and #5 Crossbar offices, or the newer 'precise' tones.
The nuances of the connections indicated that it was most definitely a #5 Crossbar.
At the time of the Great Renumbering, the only prefix in Bellevue was 291. 292 and 293 were added in the early and late 1970s respectively as the community expanded.
I'm not really sure if the 294 prefix, which served Offutt Air Force Base exclusively at the time, was actually hosted out of Bellevue, or out of Douglas. I've heard some 'in the know' people say one, and some say the other.
Prefixes at the 1977 checkpoint: 291, 292, 293. Honorable mention: 294.
The area's first #1 ESS switch was installed in Council Bluffs ca. 1970, replacing the Step offices serving 322 and 323. An additional prefix, 328, was added at the time of the cut, and 325 followed several years after, giving the main Council Bluffs downtown CO a total of four prefixes at the time of our checkpoint.
In 1971, toll-free direct seven-digit dialing was established between Council Bluffs and metropolitan Omaha.
Along with metropolitan Council Bluffs, the Manawa CO, serving prefix 366, was added to the Omaha dialing area. The Manawa office was unique in that it used 'directorized' Step switches. This was a typical up-and-around Strowger-switch type office, but with a common-control 'Director' device added. The Director was between the linefinder and the first selector. The Director returned dial tone to the subscriber, received the dialed digits, and then drove the switches appropriately to set up either an intra-office or inter-office call. This also allowed true Touch-Tone service on this Step office, as opposed to a simple tone to pulse converter. The Manawa office was the only Director Step office in the Omaha area.
Council Bluffs also had toll-free calling to a few nearby rural CDO's, all on the Iowa side, in Silver City/Mineola (526), Crescent (545), and Underwood (566), but these remained toll calls from Omaha (and Carter Lake, Iowa) until the 1980s.
Prefixes as of the 1977 checkpoint: 322, 323, 325, 328 downtown CB and 366 in Manawa.
Carter Lake
The community of Carter Lake, Iowa is a geographic oddity as well as a telecommunications oddity.
Carter Lake, an incorporated village, lies physically on the Nebraska side of the Missouri River, but remained politically in Iowa when a flood, ca. 1880s, caused the river to shift.
Carter Lake has an Iowa Zip Code, residents vote in Iowa elections, and students attend Iowa public schools. Carter Lake is in Iowa, except for one telecom-related quirk.
In the subscriber dial era, Carter Lake has always been served from Omaha's Douglas Street office, and has always been toll-free to and from Omaha. Carter Lake's original dial prefix name was LAke, and those who are observant can easily see that this is simply a renamed JAckson, which was the second Panel office out of Douglas.
For some unknown reason, at a date I'm unable to precisely determine, Carter Lake subscribers were moved from the LAke prefix to the 'new' YEllowstone prefix. YEllowstone was implemented sometime prior to our 1953 beginning of the epoch. Again, those who have been paying attention will notice that YEllowstone is simply a renaming of WEbster, rinse, repeat.
At the date of the Great Renumbering in 1960, Carter Lake was spun off to its own distinct prefix, 347, in anticipation of Direct Distance Dialing.
Carter Lake, politically in Iowa, was within area code 712 and was dialable as such. However, anecdotal evidence persists that at one time the 347 prefix was dialable from outside the area as either 402-347 or 712-347.
Carter Lake has always received the short end of the stick as far as local calling area is concerned. Carter Lake's toll-free dialing options into nearby rural Iowa communities have always been fewer than those from Council Bluffs or Omaha proper.
An interesting quirk of the 347 office, noted by many phone 'enthusiasts', was that the 5000 and 9000 levels were interchangeable. You could dial any 347-5xxx or 347-9xxx number using either 5 or 9. Yes, this facilitated some game-playing with 'check for coin' procedures. :)
Toll-free seven-digit dialing remains between Omaha and Carter Lake to this day, with Carter Lake still being served out of the Douglas office.
Carter Lake, an incorporated village, lies physically on the Nebraska side of the Missouri River, but remained politically in Iowa when a flood, ca. 1880s, caused the river to shift.
Carter Lake has an Iowa Zip Code, residents vote in Iowa elections, and students attend Iowa public schools. Carter Lake is in Iowa, except for one telecom-related quirk.
In the subscriber dial era, Carter Lake has always been served from Omaha's Douglas Street office, and has always been toll-free to and from Omaha. Carter Lake's original dial prefix name was LAke, and those who are observant can easily see that this is simply a renamed JAckson, which was the second Panel office out of Douglas.
For some unknown reason, at a date I'm unable to precisely determine, Carter Lake subscribers were moved from the LAke prefix to the 'new' YEllowstone prefix. YEllowstone was implemented sometime prior to our 1953 beginning of the epoch. Again, those who have been paying attention will notice that YEllowstone is simply a renaming of WEbster, rinse, repeat.
At the date of the Great Renumbering in 1960, Carter Lake was spun off to its own distinct prefix, 347, in anticipation of Direct Distance Dialing.
Carter Lake, politically in Iowa, was within area code 712 and was dialable as such. However, anecdotal evidence persists that at one time the 347 prefix was dialable from outside the area as either 402-347 or 712-347.
Carter Lake has always received the short end of the stick as far as local calling area is concerned. Carter Lake's toll-free dialing options into nearby rural Iowa communities have always been fewer than those from Council Bluffs or Omaha proper.
An interesting quirk of the 347 office, noted by many phone 'enthusiasts', was that the 5000 and 9000 levels were interchangeable. You could dial any 347-5xxx or 347-9xxx number using either 5 or 9. Yes, this facilitated some game-playing with 'check for coin' procedures. :)
Toll-free seven-digit dialing remains between Omaha and Carter Lake to this day, with Carter Lake still being served out of the Douglas office.
Friday, January 15, 2010
The New Offices
Let's discuss Ma Bell's newer physical offices which came about between our timeline start (1953) and 1977, which is a good 'checkpoint' at which things were reasonably stable again.
The westward and southwestward expansion and sprawl of the Omaha area required the construction of several new offices, beginning in the mid 1950s. A total of six new CO buildings, three of them originally #5 Crossbar and the other three #1 ESS appeared within a 20 year span between the mid 1950s and the mid 1970s.
The westward and southwestward expansion and sprawl of the Omaha area required the construction of several new offices, beginning in the mid 1950s. A total of six new CO buildings, three of them originally #5 Crossbar and the other three #1 ESS appeared within a 20 year span between the mid 1950s and the mid 1970s.
- 90th. St. and Western Avenue
The first of the newer central office buildings in Omaha was the 90th. and Western Avenue office, ca. 1955. This was a brand new #5 Crossbar office which served two new prefixes, HUdson and TErrace prior to the Great Renumbering.
The service area of the 90th. and Western office began at approximately 72nd. St. and reached westward past Boys Town. This relieved part of the load from the Izard St. office and allowed westward expansion without as many issues due to long loops.
It covered the newer suburbs such as Rockbrook, Maple Village, and Tomahawk Hills and replaced the Izard St. service in Irvington, which was still a disjoint unincorporated community.
TErrace became 391 and HUdson became 393 in September of 1960.
A third prefix, 397 was added in the late 1960s and 392 was added to the #5 Crossbar in the mid 1970s.
496 and 498 were temporarily hosted on the 90th. and Western #5 Crossbar as the 132nd. and Fort office (see below) was constructed and subscribers in part of the area to be served by the Fort St. office were migrated.
A major addition, an eastward expansion of the building and a new #1 ESS switch appeared in the late 1970s. When this was complete, 397 was moved to the ESS, 399 and 390 were added, and 398 was moved from the 135th. and Center office (below) to 90th. and Western.
At our checkpoint of 1977, the 90th.and Western office served 391, 392, and 393 on the #5 Crossbar and 397, 398, 399, and 390 on the #1 Ess. - 84th. and Harrison and 135th. and Center
'The Twins'
Two similar and very significant #5 crossbar offices were constructed in the early 1960s to expand the Omaha dialing area and to serve the westward and southwestward expansion. These were at 84th. and Harrison and at 135th. and Center.
84th. and Harrison originally hosted the 331 and 339 prefixes and served the Ralston (formerly served by O Street), La Vista, and Papillion areas, all of which had explosive growth in the 1960s and 1970s. 592 was added to the office in the late 70s, bringing our prefix count for this office at our 'checkpoint' to 3: 331, 339, and 592. 593 was eventually moved to 84th.
135th. and Center originally hosted the 333 and 334 prefixes and served a very large area of West Omaha, roughly west of I-680 from just north of Dodge south past the community of Millard, then an independent town. 330 was added in the mid 1970s.
The 398 prefix, originally used mainly for Centrex-CU for Bergan Mercy Hospital was temporarily hosted out of 135th. until it was moved to the new ESS at 90th. in the late 1970s.
Another significant temporarily-hosted prefix, 895, was temporarily served out of 135th., as the 156th. and Harrison office was constructed.
At our 'checkpoint' of 1977, 135th. hosted 333, 334, and 330. (691, 697 and others were yet to come.) - 78th. and Girard
The first of the new stand-alone ESS offices was commissioned in 1971 at 78th. and Girard and was intended to serve the somewhat-sluggish northwest expansion of Omaha. It took its service area from existing subscribers served by 90th. (391, 393, 397 at the time), Izard (551, 553, 556, 558 at the time), and Fowler (451, 453, 455, 457 at the time).
571 and 572 were the original prefixes out of 78th.
The service area was large and stretched northwest from approximately 60th. and Ames. It originally included sections of what was to be served by the 132nd. and Fort St. office (below). The 493 prefix was temporarily hosted at 78th. as the new Fort St. CO was constructed and customers for that area were migrated.
Due to the less than predicted northwest expansion, the 78th. St. office held a permanent prefix count of two (571 and 572) for almost two decades. - 156th. and Harrison
The next office was the 156th. and Harrison office, hosting the 895 and 896 prefixes. This served the Millard area, recently annexed into the city of Omaha with significant angst. 156th. took a large chunk of its service area from the 135th. and Center office and some (Westmont, etc.) from the 84th. and Harrison office.
895 had been temporarily hosted out of 135th. and Center and many of the customers in the new office's service area were migrated prior to the actual turn-up of the 156th. and Harrison office.
156th. and Harrison also 'temporarily' (for several years, actually) hosted the 593 prefix, used mostly at the time for the Centrex-CU installations at Midlands Hospital in Papillion and the Sarpy County offices, also in Papillion.
At our checkpoint in 1997, 156th. hosted 895 and 896 for general service and at the time hosted the 593 prefix for the Centrex-CU installations. - 132nd. and Fort
The third of the large ESS installations was at 132nd. and Fort, coming on line in the late 1970s. This new office took its service area mostly from portions of 135th. and Center (333, 334), and 78th. and Girard (571, 572).
A 'choke' prefix, 962, used mostly for radio call-in lines, was added to the Fort office in the late 1970s.
At our checkpoint of 1977, Fort. St. hosted 492, 493, 496, 498, and 962, three of which had been temporarily hosted by neighboring COs during the construction period.
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