What to check

In the telephone check that the wire going to the 'F' terminal is making a good connection. The 'F' wire is the common for speech both ways and, when linked with 'B' and 'G', which it is on most systems, it is the common for all phone functions.

A disconnected F with B&G will give other function failures as well.

Corrective Action

Ensure good connection at both ends of the cable.

Additional notes

There is a misleading characteristic if there is another handset off-hook on the system. You may find that you have 'blowback' (where you can hear your own voice through the handset speaker) but there is no audio to the door panel.

In a properly functioning system, there will be DC voltage between 'F' and 'L', 'F' and 'P' and an AC voltage between 'F' and '1'