Its called distintive Ring. This is the instructions from the manual -
If you have Voice Mail or a TAD (Telephone Answering Device) and want to keep
one of your phone numbers dedicated only to fax calls, you must leave the fax machine
mode at all times while using the distinctive ring feature. Here’s why:
Manual mode will never pick up a call by itself, since it is «Neutral ». When the fax
machine is in this « neutral » mode, the Distinctive Ring Feature can be activated. The
distinctive ring feature is actually an answering mode. So, do not activate FAX ONLY
mode or FAX /TEL mode while using distinctive ring; otherwise, the fax machine will
answer calls for all
Registering the Distinctive Ring Pattern
Set the fax machine to MANUAL mode.
Press to select DISTINCTIVE:SET?
, and then press Menu/Set
Press to select the prestored ring pattern you want to assign, and then press
. (You will hear each pattern as you scroll through the four patterns.)
Be sure to choose the pattern assigned by the Telephone Company.
and a link to the manual if you need it -