[Serusers] Using SER with Microsoft OCS 2007

Hello! I am interested in using SER to convert TCP SIP traffic from OCS to UDP SIP traffic that I can use with an external PSTN gateway provider. Has anyone successfully managed this? Basically, the configuration would look like OCS -> Mediation Server -> SER -> External Provider Would the Mediation Server still need an external (non-NAT'd) IP? It seems like it would, unless I use mediaproxy or RTPproxy, which would add an additional layer of complexity. I guess I am looking for some validation that what I am trying to do will work. My next question, which I can't seem to find an answer to, is how I take the TCP SIP traffic from OCS, convert it to UDP SIP, and also authenticate with that external provider. Any ideas on how to use t_relay_to_udp with authentication? Thank you! Nolan