If your faxes are not being sent -
1) Please make sure you have Internet connection as faxes are routed through the Internet. Go to Safari browser and type "www.yahoo.com" for example to see if the page load and if you have Internet connection.
2) It is possible the recipient's fax line is busy at the moment. You may want to try again at a later time when the line is no longer busy.
3) If you are using a VPN service, it may interfere with sending faxes. You might want to try turning off the VPN service and try again.