Hi Duncan,
From time to time, I've encountered that myself across different installs and environments for Linphone. However, in order to get a substantive answer, you'll need to supply the list with more info about your use case, viz.:
- OS
- Installed version of Linphone
- Bug trace may be useful -- paste the output into your reply
- Network -- maybe some basics about how/where you're using Linphone, ie., behind firewall, etc.
- Avoid special characters -- there are occasional bug reports with users inputting reg info with characters that Linphone doesn't like. Do a test case with a very simple UID + PW as a baseline just to check.
- SIP provider -- are you using Linphone's free SIP service? If so, did you validate your signup? If using another SIP service, have you successfully used that SIP address with other client apps?
Charles