Stuck with SBC config re-design

I'm reatively new to SIP & Session Border Controllers but am the sole Voice Tech in my company's telecom area tasked with setup of our Session Border Controllers for us in VoIP & FoIP. 

 

Currently my first project is to help in migrating our fax traffic to a set of FoIP fax servers, but this is being done prior to having PBXs that handle native SIP.  As a result, all fax traffic that must occur between traditional fax machines or multi-function devices that serve fax purposes, must have their traffic transcoded by a media gateway before arriving at our current Nortel PBXs.