Linda,
SIP is not necessarily a requirement for RightFax or other fax servers for that matter. In addition, it's not so much that you turn on SIP on the network as opposed to deciding which deployment model you're going to use. With RightFax, you have several options.
There is T.38 fax relay where all communications with the fax server is IP. SIP comes into play here because a PSTN gateway is typically configured to talk directly to the fax server and this communication is SIP. If you need to route calls to CCM and the fax server, then H.323 is used for CCM connectivity.
You can also do a direct T1 connection(s) to RightFax. No SIP.
The next option is MGCP Cisco Fax Relay. Call signaling for fax calls routes thru CCM via MGCP.
For more details, go here: http://www.cisco.com/en/US/products/ps6178/prod_installation_guides_list.html and check out the Installation Guide supplement for Cisco Fax Server. Cisco Fax is just a straight OEM of OpenText RightFax so they are truly one in the same.
Also give a look to XMediusFax by Sagem-Interstar. It has a great reputation as well.
Hailey
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