Symptoms
When a response group agent transfers an incoming call to a PSTN number in a Microsoft Lync Server 2013 environment, the connection can't be established.
Cause
This issue occurs because the SIP Invite message header contains the number that the call is being transferred to instead of the number of the response group.
Resolution
To fix this issue, install the August 2016 cumulative update 5.0.8308.965 for Lync Server 2013, Response Group Service.
