When the machine is in Fax/Tel mode, it will use the F/T Ring (pseudo/double-ringing) to alert you to pick up a voice call.

If you are at the machine, lift the external telephone’s handset, and then press Hook button to answer.

If you are at an extension telephone, lift the handset during the F/T Ring and then press #51 between the pseudo/double rings. If no one is on the line, or if someone wants to send you a fax, send the call back to the machine by pressing *51.