“Hello operator?  Get me Chelsea 602 please.”
  • Project:
    Convert 1A2 system to Avaya Partner ACS, preserving existing cable/wire.
  • Scope:
    3 CO Lines (2 Voice, 1 Fax), 1 Gate Line, 10 Extensions, Fax Machine, Answering Machine
  • Parts Used:
    Avaya Partner ACS R6 Module, 308EC Module, 2-Slot Carrier, (2) 66-Blocks with preinstalled jacks, (1) Standard 66 Block, Amphenol to RJ11 Converters, APC Back UPS 650, RCA 5-Disc CD Player

This project was for my Grandmother’s house.  She’s had her 1A2 system for 40+ years and up until recently it has given great service.  Line 3 on the 1A2 was giving serious audible static to the point of not being usable.  Instead of troubleshooting and fixing the old system, I figured it was more cost-effective to put in a used, but more modern system.  I chose the Avaya Partner ACS as the replacement system as it’s cheap, full-featured and I have experience with it (I’ve owned a few).

If you don’t know what an Electromechanical 1A2 system is, think of it as sort-of the OG of phone systems. It was the first prevalent multi-line phone system.  You can read more about the 1A2 at Wikipedia. Here’s a picture of a 1A2 phone:

See that crazy connector hanging off the right of it?  That’s the amphenol connector which you may remember from a Parallel printer’s connection to a computer before USB became popular.  Each 1A2 phone required a 25-pair cable to operate and terminated with an amphenol connector at the phone end.  For our project we simply disconnected the old phones and snapped on an amphenol to RJ11 adapter.  In some circumstances we had to chop the amphenol off and use a biscuit, but the majority used adapters.  The good news is when you are replacing a 1A2 is you’ll have LOTS of existing cable to deal with.

In this particular project there were two blocks that cross-connect to the KSU, both requiring retermination.  One of the blocks was in a central spot near the system in the basement (Block A) which was connected to the KSU via another 25 pair cable.  This is where the majority of extensions terminated and where Block B cross connected as well.  There was another block (Block B) in the attic powering the upstairs 3 extensions (this was a surprise we found late in the job).  My task was to reterminate the cross-connect blocks so that every phone would have it’s own dedicated 2 pairs.  In a 1A2 system each phone “shares” a series of pairs with the other phones… it’s complex to explain and Wikipedia does a better job of it.

My friend Walter (thanks Walt!) and I completed the job in about 11 hours on a Saturday.  It worked out great and my Grandmother loves her new phone system.  Check out the pics below of the before and after.  You can also read more at this thread at Sundance Communication’s phone system tech support forum where I asked pre-install questions to the experts, having never done something quite like this before.

Before & After Shots:

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