Canon MX520 series Fax Manual page 56

You can only enter numbers that have already been registered.
6. Click OK.
To continue registering fax/telephone numbers or a group dial, repeat steps 4 to 6.
• To save the registered information on the computer.
1. Click Save to PC....
2. Enter the file name on the displayed screen, then click Save.
• To register the registered information to the machine:
1. Click Register to Printer.
2. Confirm the message on the display, then click OK.
The information is registered to the machine.