> From: Chen Nir > > A quick one, what is the definition of outbound proxy for SIP? > Is it only for initial request or all request in dialog?
Commonly, SIP UAs can be configured to send all requests to some particular server, regardless of how the request are addressed. Most UAs that have a proxy server setting send all requests to the proxy server, even if the request is part of a dialog with an established route set. But RFC 3261 suggests that it is better to route requests within a dialog according to the route set rather than the proxy server. (If the outbound proxy server really wants to stay in the signaling path for a dialog, it can add a Record-Route.) Section 8.1.2 Local policy MAY specify an alternate set of destinations to attempt. If the Request-URI contains a SIPS URI, any alternate destinations MUST be contacted with TLS. Beyond that, there are no restrictions on the alternate destinations if the request contains no Route header field. This provides a simple alternative to a pre-existing route set as a way to specify an outbound proxy. However, that approach for configuring an outbound proxy is NOT RECOMMENDED; a pre-existing route set with a single URI SHOULD be used instead. If the request contains a Route header field, the request SHOULD be sent to the locations derived from its topmost value, but MAY be sent to any server that the UA is certain will honor the Route and Request-URI policies specified in this document (as opposed to those in RFC 2543). In particular, a UAC configured with an outbound proxy SHOULD attempt to send the request to the location indicated in the first Route header field value instead of adopting the policy of sending all messages to the outbound proxy. Dale
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