Gte 120b hooking into pbx help

[SneakDante]

Hello all

I've recently an altel payphone that has a gte 120b board in it. I have tried to hook it into a x link bluetooth and a grandstream ht813 to try and get a dial tone but so far had no luck.
Things I've tried so far are swapping the jumpers at array a and b from er, pr and Sr (as it has a rotary front plate.Both with having connected and  Disconnecting the relay and coin switches. And building a simple button array to replace the switches in the coin switch to press them without inserting coins.
I know I'd need to build a coin trunk simulator if I wanted to actually use the relay properly but my plan is to just have it on the wall at home, and have it connected to my pbx via one of my grandstream fxs that can handle the pulse dialing.

The phone is getting something because I get the off hook alarm if I connect it up and leave the handset next to the phone but otherwise I don't get any other function.

Any leads or documents would be alot of help

[Westrex]

Have you tried checking the voltage and current output of the Xlink and Grandstream? A standard POTS line is about 48 VDC (90-ish VDC when ringing) and the line should ideally have more than 22 mA of current.  Also, could you post some pictures of the inside of the phone so we can visually see what's going on in there?

Also, you may want to see this post for more help.




Here are some documents relating to the AE/GTE 120 series if they're any help:

- General System Practice 476-201-100 (120A specific): link

- GTE Technical Journal - January, 1972: See Attachment 1

- General System Practice 476-201-100 Addendum Issue 1 (120A specific): See Attachment 2

- General System Practice 476-201-100 Addendum Issue 2 (120B specific): See Attachment 3

[dsk]

I did also struggle with that, try to read this thread. It may hopefully solve it.
https://www.classicrotaryphones.com/forum/index.php?topic=11846.0