Seriss Corporation - 1A2 Key Phone System Equipment

 1A2 "Single Board" KSU
These boards are an easy "single circuit board" solution to managing multiline "1A2" business phones popular in the 1950's - 1980's in the United States and other countries, collectively called "key systems".

The current version of this board is REV-J6A.

Board revisions are, in progression of new-to-old:
J6A, J5A, J5, J4, J3, J2, J1, H / H1, G1, G, F1, F, E, B.

You can see the entire revision history which describes in great detail what's different in each board revision.

If you're interested in these boards, contact erco@seriss.com with the email Subject: "1A2 KSU Inquiry" and I can supply ordering info for fully assembled/tested boards. Include info on which phone models you expect to use with the board.

Amphenol ⇌ RJ45 Cable Reducer & Expander
These boards let you use simple RJ45 cat5/cat5e network cabling to interconnect 1A2 phones to the Seriss KSU without needing 25 pair cables or 66 blocks.

Lines 1,2,3,4 and 5 (Intercom) as well as bells and buzzers can be carried over three RJ45 cables without any special punch blocks or configuration. Fewer cables can be used for fewer lines. (DEC 2025 UPDATE: In REV-E and older, Line 4 was not supported. This changed in REV-F and up)

Designed mainly for use between 1A2 phones and the Seriss KSU.
Click here for details.

If you're interested in purchasing these boards, contact erco@seriss.com with the email Subject: "1A2 RJ45 amphenol adapters inquiry" and I can supply ordering info for fully assembled/tested boards.

Seriss 82B Connection Block
(for 4A Speakerphones)
This Seriss 82b connection block board is a modern re-implementation of the Western Electric 82b connection block used to interconnect 4a speakerphone components with 1A2 key telephone sets, such as the 565 / 2565 Western Electric sets, and the 5 line Touch-A-Matics.

If you're interested in purchasing these boards, contact erco@seriss.com with the email Subject: "1A2 82B block inquiry" and I can supply ordering info for fully assembled/tested boards.

Include your phone set model# and 4A speakerphone components you plan you use. Example: a 2565 phone set with a 108a speaker, 680a transmitter, 85B1 power unit. Make sure speaker and transmitter have intact connectors at the ends of their cables!