sundance-communications.com/forum Forums TDM Business Telephone Systems Comdial Telephones & Systems DX-80 Has dial-tone but cannot tone or voice out

I have a COMDIAL DX-80 system that has had this issue 3 times now. Unplugging the unit and flipping the switch a few times to discharge capacitance then plugging it back in has resolved it twice. No more does this work

Basically when you lift the receiver at any of the 6 phones in this location you can get a dial-tone but voice or tone will not transmit.
When pressing buttons the dial-tone will go silent until I stop pressing keys. Nothing happens with keys that I press. If I call the main line with my cell phone, all lines will ring but if I answer on the COMDIAL phone I cannot hear my voice transmit to my cell phone.

This is on every phone and all 6 lines.

Troubleshooting done:
Got an electrical spec sheet for all modules in the system. Power, transformer, and all modules show on multi-meter within tolerances. Powered off and removed all modules one by one and rebooted and tested all the way down to the CPM module and base lines module hoping to get a tone to register or voice to send out. No good. Figured maybe firmware or logic circuit or programming bad. Did a cold start and wiped all programming. Set the jumper back and rebooted. Still same issue. Phones will ring but when answered cant send out voice or tone. Dead silent.

Tried programming. Can enter programming menus with the default ######## password from any phone so the system must see some tone response from the phones!

Contacted TDS in Mesquite NV. They sent a tech that hooked up to the 66 block and found their lines functioning ok.

Gave up.

Hard to support these systems anymore but this one has worked about 12 years now and my client is loathe to replace it.

Any help would be graciously appreciated.

If the DT works ok, then time to replace, or run there business with cell phones.

Time to replace the CPM Module? Sourced one for 50 bucks.

Try it

Sold too many with too many problems. cut your losses and sell them a new system. maybe NEC

Still have parts for these systems. If still needed send me a Private Message.