[Serusers] 305 Use Proxy

Hello, I am trying to setup a redirecting proxy server with Ser, but I find that my GXP-2020 phone gets into an endless loop. Is this common? The phone is configured to use my ser service which is set as a proxy. If it tries to dial things that this proxy shouldn't handle, it sends back a "305 Use Proxy" response. The phone seems to ignore the proxy and tries again. 1) Is it common for the proxy redirection not to work? I've seen it being ill-advised on iptel.org because the RFC isn't too clear how it works. 2) What would be the proper formula to get Ser to send back a proxy redirect? I may be approaching it wrongly, but I cannot find much documentation about it online. Thanks, Rick van Rein OpenFortress