I use the swedish VoIP service provider Digisip. I can't get Express Talk to register with their proxy. I get a "401 Authorization failed" error code back.
I suspect that the Digisip proxy wants both the SIP Username (my telephone number) and in response to the "401 Authorization failed" challange wants a separate "authentication user id". Digisip provides such an "authentication user id" (They call it "customer number") to be entered in Digisips recommended software.
Software like X-Lite also provide a field for an "authentication user id" but I don't understand how that id can be entered into Express Talk.
Am I out of track? Any suggestions?
/Leif