Brother MFC-9420CN - Manual (Page 68)

Receiving a fax
6 - 7
6
For Fax/Tel mode only
When the machine is in Fax/Tel mode, it will
use the F/T Ring Time (pseudo or
double-ringing) to alert you to pick up a voice
call.
Lift the external telephone's handset, and
then press Hook to answer.
Using the remote codes
If you hear the fax machine double-ringing
when you are at an extension phone, you’ll
need to lift the handset and then press the
Telephone Answer Code (#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 the
Fax Receive Code (
51).