The SIP message routing from
IM and Presence to
Microsoft Office Communicator is based
on the Record-Route header added by
Microsoft OCS in the initial
IM and Presence resolves the hostname in the Record-Route header to an IP
address and routes the SIP messages to the
Microsoft Office Communicator client.
In addition the transport type on
IM and Presence should be the same as the transport type configured on
Microsoft OCS for the
IM and Presence route (either TLS or TCP respectively).