Hi Rick,
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.
unfortunately the usage of 305 is totally under specified. And I haven't it being used in the field ever. Anybody else maybe?
On a first look this seems to be the perfect response if you want to make the sender of a request to retry this request on a different proxy, BUT: - is a proxy on the path back allowed to consume the 305 and retry it by himself on behalf of the originator? - or is only the originator (UAC) allowed to follow the URI from the reply? - if it is only the originator: how can the originator assure that the request will traverse exactly the same path except for the last hop? Use a Route header? But when it receives the 305 response it does not know which path the original request took. - in case of the the originator trying to follow this reply: what should the UAC do in case it uses an fixed outbound proxy? Use a pre-loaded Route header with two entries? - and the biggest question: how should the URI look like which you send back in the 305 response? Just the URI of the proxy without usernames? Or should it be the complete URI which should be retried at that proxy?
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.
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.
I would recommend you to avoid the 305. Which also means there is nothing like a proxy redirect. You could either try to use a 301 response instead. Or you just configure the proxy to froward the request to the correct proxy instead of replying with a 305.
Best regards Nils Ohlmeier VoIP Freelancer