For a UCMA based application like SEFAUTIL Server to work correctly you will need to have the Skype for Business Server (Lync Server) DNS records in place: You will need to have one of the following records in place that resolves to your FE pool/server.

  • SRV    _sipinternaltls._tcp.{yourdomain.com}
  • SRV    _sip._tls.{yourdomain.com}
  • A         sipinternal.{yourdomain.com}
  • A         sip.{yourdomain.com}


If this is not setup you might get errors such as:
Microsoft.Rtc.Signaling.OperationFailureException:Automatic server discovery for the given sip user uri failed.