Canon MX870 Series User Manual page 47

If Manual/auto switch is set to ON, set RX start time longer than the time before the answering
machine starts playing the answering message.
After making this setting, we recommend that you confirm that messages are recorded
successfully in the answering machine.
When FAX priority mode is selected:
When the call is a fax:
The telephone will ring when a call incomes.
The machine will receive the fax automatically.
Note
Other options
Set the machine not to ring the telephone.
Change the number of times to ring the telephone.
See
Settings for Receiving Faxes
When the call is a voice call:
The telephone will ring when a call incomes.
When the machine detects a voice call, the machine will ring.
Pick up the handset, and talk on the telephone.
(1)
Note
Other options
Set the machine not to ring the telephone.
Change the number of times to ring the telephone.
Change the number of seconds until the machine starts ringing.
.