When configuring Lync Server 2013 UM integration with Exchange server, the standard dialplan security configuration is configured as “Secured”. But, recently i came across with the issue where the dial plan security is set to “Secured” and the UM Service and the UM Call Router services are set to use “TLS”, i get the below error event on Lync front end server.

And when logged in to the Exchange Database server, there were plenty of warning event messages complaining that the voice encryption does not match with the Dial Plan configuration.

Thinking about the Dial Plan’s security configuration, It came to me that, then the services are set to use “TLS” instead of “Dual”, then the Dial Plan muct be configured as “SIP Secure” or elase it’ll come up with the abouve error.

After changing the Dial Plan security configuration and restarting UM service on both the Exchange database servers and UM Call Router on CAS server, it finally started working.

This wouldn’t be a problem if the services are set to use “Dual” instead of TLS. But, it’s recommended to use TLS as all traffic between Exchange servers and Lync servers are encrypted