Hi Rashida,
You will likely run into compatibility issues between CUCM 6.0 and Exchange 2007. CUCM 7.0 introduces SIP T.38 interoperability with Microsoft Exchange.
Exchange switches a call from audio to T.38 fax by sending SDP with two "m=" lines, one to terminate audio and one to enable fax session. CUCM 6.0 does not use this method, and interprets it as an audio request to terminate the call so fax calls fail.
In CUCM 7.0, the implementation of T.38 interoperability with Microsoft Exchange enables the system to switch a call from audio to T.38 fax.
The following steps show how the Microsoft Exchange Server establishes a call to a fax machine:
a. The exchange server establishes an audio call with the fax machine.
b. The fax machine send fax tones (CNG) to the exchange server.
c. The exchange server recognizes the fax tones and tries to renegotiate the call as a T.38 fax call.
Cisco Unified Communications Manager Administration allows you to configure a SIP Profile that supports T.38 fax communication. This profile applies to SIP trunks only, not phones that are running SIP or endpoints.
Cisco Unified Communications Manager Administration Configuration Tips
The Outgoing T.38 INVITE Include Audio mline parameter allows the system to accept a signal from Microsoft Exchange that causes it to switch the call from audio to T.38 fax. To use this feature, you must also configure a SIP trunk with this SIP profile.
GUI Changes in CUCM 7.0
To access the Outgoing T.38 INVITE Include Audio mline parameter, choose Device > Device Settings > SIP Profile.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/rel_notes/7_0_1/cucm-rel_notes-701.html#wp582805
Hope this helps.
Regards,
Michael.
