SIP FAQ : SIP Functionality :
When do I use a proxy server vs. a redirect server?
You use a proxy when you want to control processing of the call from the point you receive it, and forward. A proxy can see the provisional and final responses to the request. It can record route so that it sees whats going on during the call. A redirect server, however, hands off control to the device that sent it the INVITE. It will never see the final response to the request, and not be contacted again for the remainder of the call. Its a one-shot deal.
As such, redirect servers are really good for high volume, lookup style transactions. They can almost be considered a form of database query, albeit a SIP specific one. Proxies are generally needed for services and more complex routing problems.
2000-Nov-14 10:50am jdrosen@dynamicsoft.com
Does SIP support video or multimedia conferences?