I would guess it is more of a phone issue, ala Dial 9 to call out.
But a guess is worthless, fax is just a phone call, so listen to it send.
At the printer login as admin via username = admin and password - 1111
Machine Status > Tools > Service Settings > Fax Service > Fax Volume.
Crank up the volume and send a fax, you will most definitely find out whats up with it.
We have a Xerox WC 7830 that will receive faxes without any issue but we aren't able to send faxes out. This is a new issue that we are having. It isn't an issue with the recipient's machine because we've tried sending to multiple numbers/machines. The fax confirmation report simply states: "Status.......FAILED. Unable to connect to remote server."
Any suggestions/ideas? And I am not technologically savy so please use layman's wording -- just think "Fax Troubleshooting for Dummies." Thanks!