[Serusers] Rewrite Contact header

Can someone give me some direction as to how I can get SER to functin as a basic B2BUA?...a document, how-to, etc? If that is not readily available then I wonder if there is some way that I can get SER to statefully rewrite the Contact header when it relays messages? The reason for this is that I want all of my UAs to interact only with/through SER and not directly with each other. Something like this: UA1 SER UA2 IPaddr1 IPaddr2 IPaddr3 | ----------> | | | INVITE | | | contact: name@IPaddr1 | | | | ----------> | | | INVITE | | | contact: name@IPaddr2 | ..... ..... ..... | | <---------- | | | BYE | | | ruri: name@IPaddr2 | | <---------- | | | BYE | | | ruri: name@IPaddr1 | | | | | Without rewriting the contact header I get the following which is undesireable: UA1 SER UA2 IPaddr1 IPaddr2 IPaddr3 | ----------> | | | INVITE | | | contact: name@IPaddr1 | | | | ----------> | | | INVITE | | | contact: name@IPaddr1 | ..... ..... ..... | <---------------------------------- | | BYE | | ruri: name@IPaddr1 | Thanks to all for contributing to a really nice open source system. Regards, Robert Brown