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...
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:
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
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
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
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
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
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 -
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!