Military Phone TA-1042 

The CB (called common battery) mode still uses the standard interface but it switches the phone to a mode where it expects a switch to be connected on the other side of the 4 wire interface. In the LB mode it will trigger a ring on the other phone but in the CB mode it attempts to negotiate with a switch on the other end of the line. The port on the bottom is actually an accessory port that was used to connect peripherals; it provided audio access and direct access to the digital bitstream. There are fax machines compatible with these and there was a computer terminal available as well. If you’re curious my friend and I implemented a switch for these that can interconnect them with a computer. Finishing up a video at some point the next few days.

The TA-312s are simple 2 wire tip and ring and use local batteries and can also be connected to the phone system.

Very cool, great of you to include the info flash override.

Yes, those are standard radio hand mics.

If the distance between Point A & B goes beyond 1000 feet, is there attenuation and is there some way to boost the signal?

is that P25? just kidding, cool toys!

$80 😭 these are like $200 now.