Last week I had trouble dialing out of Lync to the PSTN network. Incoming calls and internal Lync calls worked fine, but the outgoing calls failed with this error:
ms-diagnostics: 10407;source=”internallyncserver.contoso.com”;reason=”Gateway responded with 407 Proxy Authentication Required”;component=”MediationServer”;SipResponseText=”Not Acceptable Here”;GatewayFqdn=”siptrunkprovider.somewhereoninternet.com”
ms-diagnostics-public: 10407;reason=”Gateway responded with 407 Proxy Authentication Required”;component=”MediationServer”;SipResponseText=”Not Acceptable Here”
ms-trunking-peer: siptrunkprovider.somewhereoninternet.com;User-Agent=”OpenSer (1.1.1-notls (i386/linux))”
I’m using a Sip trunk provider, and the problem was that they authenticate me, by my outgoing IP address of the Lync mediation server. That’s not it self the problem, but the problem was that one of my colleagues changed my firewall, so I was coming from a wrong IP address, and therefore I got rejected at my sip trunk provider. So after changed the firewall so I came from the correct IP address it worked again.