Not necessarily, Jim. Their last 1A2 intercom systems were the 494A single-path card or the 6B intercom system. Both were highly-sophisticated for the time and lasted well into the 80s. Both were solid-state, as in no moving or adjustable parts whatsoever.

The main reason that the Bell System gave up on further development of these devices was because third party manufacturers were able to provide comparable equipment at a lower price. For example: Tone Commander's ML-8000 multiple path intercom system was much smaller (about a quarter the size of the 6B) and about a quarter of the cost. The Bell System saw the writing on the wall with regard to the impending divestiture and did the math.

Wow, what a side track of a thread. Still an informative one. I'm guilty as charged.

Now, back to those diddle sticks...

Ed Vaughn, MBSWWYPBX