If INVITE authentication is turned on at Brekeke SIP Server, is the authentication information correctly set on UA?
Please check your devices manual for the appropriate settings.
When Brekeke SIP Server and UA2 are on different networks from UA1.
When UA2 is on a local network, [NAT traversal] > [Keep address/port mapping] should be set to ON in the [Configuration] menu to resolve NAT traversal on UA2 side. The setting doesn’t matter if UA2 can use STUN, and STUN supports the router(NAT)’s type on UA2’s side.
When UA1 and UA2 talk through Brekeke SIP Server and another SIP server:
Please check that your Dial Plan is set correctly.
Additionally, Brekeke SIP Server does not support multi-staged authentication
so concerning communication through multiple SIP servers, please ensure that authentication will be done through only one server. You can disable authentication for specific devices in the Dial Plan ($auth=off).