GTE/Quadrum COCOT Board

[commoncathode]

Hello,
I recently came across a lot of payphone equipment, including some GTE/Quadrum housings with the chassis boards removed for shipping. I assumed they were COCOT boards, but now I'm not sure. I can't seem to find anything about them online, and they don't look enough like any of the common boards from Protel or Elcotel.
There appears to be a spot to connect AC power, since there's a bridge rectifier and bulk cap on board. The lowermost connector appears to be shared with the telephone line and the escrow solenoid, but I can only guess at the pinout.
Anyone know what these boards are, and if there's any documentation out there for them?
Thanks!