[comp.dcom.telecom] Question About Centrex

cml@cs.umd.edu (Christopher Lott) (05/06/91)

While helping a friend move, I got a good look in the basement phone
room of a large (16 floors, some 15 apts/floor) apartment building.
What I didn't understand what that it was much more than a bunch of
punchdown blocks, and there was a prominent sign "to C&P installers:
this is a Centrex system" or something like this.  Now he didn't have
to dial anything special to reach an outside line, and as far as I
know, there was no special anything about his phone.  No single digit
to reach the doorman, and when the front desk wanted to reach him,
they had to dial (what looked like) a full seven digits.

So what gives?  The installation was quite large; is it possible that
they have a small number of trunk lines coming in to that spot?  A
mini-switch!?  Sure was a *lot* of wire in that room.  Several very
large (100-pair?)  cables coming in and a lot of punchdown blocks.
Even found his line on one ;-)


chris...


[Moderator's Note: It may be they had a front door to apartment
intercom phone system with the equipment in the central office and
dedicated pairs to each apartment. That system, frequently called
"Enterphone" is a type of centrex.   PAT]