Hey,
I recently got hold of a couple of rotary phones and as a project, want to build some hardware and software to upgrade the rotary phone so that it can be used over VOIP.
The way I see it, the best repeatable approach would be to create a small box, with a raspberry pi and a custom pcb, with a 4 wire BT 413A connector as input, and an ethernet POE connector as the other input. I would like to access all functionality of the telephone, I.e. pulse dialing, bell ringer, etc.
I am trying to understand the docs around the telephone but I am not sure which wire does what, in the 413A cable, it seems that there are 2 cables for the speaker and the mic, a ground wire, and a bell wire (I am not sure this is even accurate). I understand that the pulse dialing works by checking continuity between the speaker and voice wire, and this could be done with a pulled gpio input.
I think that the voice and mic can be interfaced digitally by wiring them into a TRRS aux to USB cable, and then into the PI, and the 50VAC could be made with a Boost converter attached to a 12 V POE input, then oscillated.
Does anyone have any pointers or has made something similar with a raspberry pi?
I recently got hold of a couple of rotary phones and as a project, want to build some hardware and software to upgrade the rotary phone so that it can be used over VOIP.
The way I see it, the best repeatable approach would be to create a small box, with a raspberry pi and a custom pcb, with a 4 wire BT 413A connector as input, and an ethernet POE connector as the other input. I would like to access all functionality of the telephone, I.e. pulse dialing, bell ringer, etc.
I am trying to understand the docs around the telephone but I am not sure which wire does what, in the 413A cable, it seems that there are 2 cables for the speaker and the mic, a ground wire, and a bell wire (I am not sure this is even accurate). I understand that the pulse dialing works by checking continuity between the speaker and voice wire, and this could be done with a pulled gpio input.
I think that the voice and mic can be interfaced digitally by wiring them into a TRRS aux to USB cable, and then into the PI, and the 50VAC could be made with a Boost converter attached to a 12 V POE input, then oscillated.
Does anyone have any pointers or has made something similar with a raspberry pi?
Statistics: Posted by picoder90 — Wed Apr 09, 2025 7:50 pm — Replies 5 — Views 119