Other Technical History

The following is more technical history on telephone systems of the past. These are personal observations of the Telephone World webmaster and not necessarily accurate.


Other Technical History

My experience with phone systems were not limited to that of North Pittsburgh Telephone Company. I observed many different kinds of phone systems over the years and each one had its own uniqueness to it. Here is a brief summary of what I've observed over the years...

Bell Telephone Pay Telephone Instruction Cards

Up until the late 1980's, Bell Telephone's pay phones had a color code scheme on the top and bottom instruction cards to inform you of how the phone operated:

Blue Card: Phones that were on ESS systems (#1ESS/1AESS or #5ESS) or some #5 crossbar systems were loop start and "dial tone first". This meant you picked up the phone, got a dial tone and then dropped in the money to make the call. Operator Assisted calls, toll free calls and calls to 911 did not require a coin deposit.

Example of a blue instruction card
Source: Phonebooth.us


Brown Card: Phones that were on some #5 crossbar systems were ground start. This means you must deposit money for the phone to even work (these were known as "coin first"). You picked up the phone and you get "silence" (a little bit of background noise was always there) and the touch tone pad was non functional. If you inserted a nickel or dime, the phone would work but you could not make a local call (since at that time it required a quarter). However, you could dial a long distance or operated assisted call.

Example of a brown instruction card
Source: Phonebooth.us



Red Card: Phones that had a red card were on Bell System CDO (Community Dial Office) switches. These systems required you to dial the call and then deposit the money after they answer (known as "post pay"). The only place I saw this in the 80's was a very rural place in West Virginia.

Cannonsburg, PA - Circa 1985

Prior to the mid-1980's, Cannonsburg (Bell Atlantic) had a #5 crossbar system. When a person made a long distance call from a pay phone (either 1+ or 0+), you got one or two #5 crossbar rings, then it went through the process of a long distance call through the nearest tandem. This may be some sort of "pacifier" to satisfy the customer while the crossbar switch was sending the call to the tandem via MF digits.

Greensburg, PA - Circa 1983

Greensburg, PA (Bell Atlantic) also had a #5 crossbar until the mid-80's. When you dialed a long distance call, you did not dial a "1" first. In fact, if you tried to dial a "1", the dial tone would not break. All you dialed for direct-dial long distance was 7 digits (within area code) and 10 digits (outside area code). It has been reported that Greensburg was one of the first #5 crossbar switches with DDD (Direct Distance Dialing).

Olympia, WA - 1970s and 1980s

Olympia, WA (US West/Qwest) had a mix of #5 crossbar and 1ESS/1AESS switches. You could look in the phone book and find out that only the ESS switches could dial international numbers, while the #5 crossbar could not.

Another difference was that at some pay phones allowed you to press the # key repeatedly and would sit there silent, while others would return a reorder (fast busy). Not sure which one did what, though I suspect the ESS returned the reorder.

Onaga, KS - Circa 1984

Onaga, KS (then Sprint/United Telephone, now Blue Valley Telecommunications) was a very early step CDO (Community Dial Office) system (Area Code 785 prefix 889). The town had less than 1000 numbers and were assigned in the 4xxx grouping (pay phones were 9xxx). It was the first time I had encountered a "step" dial tone. (I thought the system was broken at first since I was used to the normal dual-tone dial tone).

Before direct (long) distance dialing (DDD), dialing a call only required the last 3 digits of the phone number, the other digits were absorbed. When they retrofitted the system with DDD capability, they encountered a problem. All the 41xx numbers had to be changed to 71xx. (4xxx could still be dialed with the last 3 digits, but 71xx required 4 digits). This was due to the fact that when you dialed a "1", you left the step switch and instantly went on a microwave trunk to the toll tandem. When you dialed "41", it thought you just dialed a "1" since the first 4 was absorbed. After you completed dialing the long distance call, you heard a stream of very fast MF tones. (more than likely it was the ANI of the originating number)

The pay phone just outside the switch office was of the 92xx series. This phone was "post pay" style. I figured out that the 92xx could be dialed as 42xx since both the leading 4 or 9 were absorbed. Long distance calls (1+) weren't allowed. You could dial a 0+ call though. Of course operators did not understand when you dialed 0+ may have wanted to dial 1+ but the phone wouldn't let you dial it. Operators also didn't know that you could dial the phone as 42xx and allowed collect calls to the phone when dialed as 42xx but not as 92xx.

Dialing 4200 or 4201 brought silence. This may have been part of a bridge. Of course it drove operators nuts when you tried to make a collect call since it never rang.

Of course it was ironic that the phone book told you to dial all 7 digits. I wonder how many dialed only the last 3 or 4 digits of a phone number until they converted to a DMS-100 in the early 90's.

Indian Head, PA - Circa 1985

Indian Head, PA (Indian Head Tel. Co - Area code 724 prefix 455) is a small independent Telco about 60 miles east of Pittsburgh, PA. It too was an step CDO office. Pay phones were post pay. The strange part of this one was that the ring was real distinct and hard to hear. It seemed to be the ringing voltage returning to the calling party without any attenuation. Again, drove operators nuts since they couldn't hear the ring!


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