Set Up Service Parameters
The SIP message routing from IM and Presence Service to Microsoft Lync is based on the Record-Route header added by Microsoft Lync in the initial request. IM and Presence Service resolves the hostname in the Record-Route header to an IP address and routes the SIP messages to the Microsoft Lync client.
In addition the transport type on IM and Presence Service should be the same as the transport type configured on Microsoft Lync for the IM and Presence Service route.
Select the IM and Presence server.
Select the service Cisco SIP Proxy.
Verify that the following parameters are configured correctly: