TELECOM Digest OnLine - Sorted: Re: Bell System Interconnect Paging Systems?

Re: Bell System Interconnect Paging Systems?

jsw (
Tue, 11 Jul 2006 12:22:26 CDT

> I was wondering if the Bell System supplied the paging system, music
> player tape recorder, or allowed a private interconnect (one of the
> rare exceptions where Bell allowed physical interconnects).

> Would anyone know if such paging systems were allowed to be
> independent and connected into the switchboard?

I worked at a major medical center for 13 years, spanning the late
70's to the early 90's. I was not in the telecom department, but I did
have a very good idea of how the campus phone systems and paging
systems operated. ;-)

When I first came aboard, the campus was served (??) by Centrex-CU off
of an aging and quirky 101 ESS on campus. Many departments had their
own (meaning serving them only, but owned and maintained by Ma Bell)
key systems. There was a mix of rotary and touch-tone on campus.

Ma Bell actually stationed two techies semipermanently on campus. They
had a small 'office' in a room off of a steam tunnel, with their stash
of cables, KTU parts, etc.

Our main paging system was totally independent of Ma Bell. It was
based on a huge honker Crown amplifier and hundreds of speakers around
the campus. The operators had paging microphones on their consoles,
but they did not connect with Ma Bell.

However, several departments had their own departmental paging systems
which *WERE* connected to Ma Bell. In these cases a departmental amp
would be fed from a 600 ohm feed from the main campus paging system
and another twisted-pair 600 ohm feed from Ma Bell's key system. To
page locally, a code was dialed on the departmental intercom key and
that cut into the departmental paging system. Both rotary and
touch-tone phones were supported. When TT was used for a page, it was
often obvious with a very loud TT burst as the page began.

I don't remember any black box or dedicated interconnect device for
these. IIRC, twisted pair frame wire ran right from the KTU punch
block over to the amplifier cabinets.

> Also, my old hospital PBX was quite regimented in Bell System dial.
> Page operators used brief exact simple phases: "Dr Jones 536"

They usually kept pages short and to the point. There were two special
'code' pages. 'Dr. Red' was a fire alarm, with the location Dr. Red
was supposed to report to immediately being the location of the fire.

'Dr. Blue' was for code blue, or a cardiac incident which scrambled
the code team.

We converted to Centrex-CO in the early 80's. Same phones, same
dialing plan, but all extensions cabled to the CO about two miles
away. (The campus straddled a CO boundary. Pay phones in some
buildings were served out of a different CO than the regular office

In the late 80's the Med Center bought their own switch, a Definity of
some sort. Almost everybody got their own 2500 style desk set with
their own DID number. Just before I left, four-digit dialing gave way
to five-digit dialing as the campus expanded. There were still many
rotary dial phones on campus until the new installation.

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