[Linphone-users] linphone stopped working with Ringcentral

[Grant]

I've been using linphone-3.4.3 on Gentoo Linux for outbound calls with
the Ringcentral "digital line" service for a long time.  All of a
sudden this week it doesn't work.  I called Ringcentral tech support
but they refused to troubleshoot because I'm not using their
proprietary client which is of course Windows-only.  This is the error
I get:

Registration on sip:sip.ringcentral.com failed: no response timeout

I've shut down the firewall with no change in behavior.  Any ideas for
troubleshooting this?

- Grant