Outbound calls are the most basic call flow, and is a great place to start when testing.
If your T.38 implementation (or SIP network) allows you the ability to record the audio of an outgoing call, please capture and listen to that, and check for recorded messages that your fax software might not be hearing.
If you still can't place outgoing calls, make sure there's no firewall or other security device blocking your outbound communication attempts to our SIP proxy server(s).
If you still have problems, submit a problem report to our support ninjas and we'll get you fixed up.