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From: rees@pisa.ifs.umich.edu (Jim Rees)
Newsgroups: comp.dcom.telecom
Subject: Switching Office Open House
Message-ID: <15250@accuvax.nwu.edu>
Date: 4 Dec 90 20:56:35 GMT
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Reply-To: rees@citi.umich.edu (Jim Rees)
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X-Telecom-Digest: Volume 10, Issue 868, Message 3 of 8


I just went to an open house at the Ann Arbor office of Michigan Bell.
If you ever get a chance to do this, I highly recommend it!  This
office has a 1ESS serving five exchanges, a 1A serving four, and a
5ESS serving eight.  The 1A is four times the size of the 5 and serves
half as many lines.  The 1 is already considered obsolete (it's 17
years old, same as my Buick) and is slated to be replaced by the 5 in
six months.

I won't go over the mundane details.  The things that surprised me
were the small size of the battery backup, the large size of the cable
vault (one city block long, filled with 300 pair cables), the extreme
small size of the dry air supply for the pressurised cables, and how
much space is devoted to distribution bays.  I expected the switches
to be small compared to all the cables and wires, and they certainly
were!  The 5ESS has a capacity of 160,000 subscriber lines (not all on
local loops, most come in on SLC-96) and would almost fit in my living
room.  Well, maybe my basement.

I was disappointed that the people we got to talk to didn't know much
about the equipment, they were mostly business office types.  But I
had a nice long talk with an outside plant guy who was full of stories
about cable breaks and how to splice a 1200 pair cable.

I knew that offices were being consolidated but was a little surprised
to learn that this one office covers almost the entire county except
for an island of GTE.  They seem to be tearing out individual 5xbar
switches and replacing them with muxes to the 5ESS.  There is still
one SxS in S.E.  Michigan, in the New Boston office.  In spite of the
concentration of switching equipment in Ann Arbor, there is no one on
duty here at night.

As a computer guy, one thing intrigued me.  Can anyone tell me about
the "1ESS memory card" that is just a piece of aluminum the size of a
sheet of notebook paper?  It doesn't seem to have any electrical
contacts, but you can see little squares on it that might be
individual bits of magnetic memory.

After nearly ten years of reading TELECOM Digest I finally got to see
what some of this stuff looks like.