Have a customer with an older SBX system. Recently have complaint about using the speakerphone, intercom calls work perfectly, but external calls you can hear the external party but caller can not hear anything. This seems to be happening on all stations.
Phones are not muted but that is the way it acts.
any suggestions are appreciated.

If the phones are not muted than the volume must be very low. PGM 411 has gain controls. They are laid out like a grid. Using admin software you can change the dti speaker to acob volume, default is 26, raise it a couple of steps at a time, reset system to take effect. There is a separate setting for both directions, so make sure you adjust the correct one.

Thanks. Will check that out.