Try one or more of the following:
From the home screen, touch Settings > Fax.
In the Fax Mode menu, select Analog.
You may have problems with your phone line.
Cannot send a fax? Changing the printer fax mode or contacting your administrator can help you solve this problem.
Here are troubleshooting steps when unable to 'Send' a fax with Laser Multifunction Printers (MFPs).