Hi Richard, If you are using openser with TCP/TLS enabled then Openser will close the tcp/tls connection after couple of minutes of inactivity by the phone. Either we have to change the code of openser to increase the tcp inactivity timer or change phone to re-register every 80 seconds or so. Otherwise the tcp/tls connection shall get closed and no further calls can be placed after that. My suggestion would be just place a single call & observe. See if it happens of a single call.