Canon JX510P Guide D'utilisation page 55

Note
When forwarding is not possible:
You can set the fax to redial the forwarding number a certain number of times at specified
intervals when forwarding is not possible, such as at times when the forwarding number is busy
or the phone is unattended. If forwarding is still not possible after the fax redials the forwarding
number the specified number of times, the forwarding setting will be temporarily canceled.
However, the fax will dial the forwarding number again when any new telephone messages are
received.
After any recorded messages have finished playing, if you do not enter a remote command, the
call will be disconnected.
52 Using TAM Mode (JX510P only)