Below are a few steps to try when Caller ID is not working on the Durafon though working on a different analog phone set:
1. Verify if caller ID works when external/high gain antenna is removed and rubber/stock antenna used. If caller ID works, the external antenna should be grounded by its own separate ground in order to avoid the building ground interference. If Caller ID does not work after replacing the external antenna with the rubber antenna verify Caller ID service from phone company to be operational and using the Bellcore 1 or 2 protocol.
2. If it's a Durafon PRO system, already has caller ID service working and is behind a pbx system, then all you need to do is turn ON Line Detect. MENU, 1 (System), 3 (Line Detect), 1 (ON). The way, Caller ID will not work if there is a group assigned to a Line.
3. If on a PBX, set the Caller ID setting on the PBX to FSKC.