Adam Roach <adam@xxxxxxxxxxx> writes: > To be clear (and this is an easy mistake to make, since the sections and > their contained steps are huge), Pete is referring to the long-form > version of step 6 in section 16.7 here. See RFC 3261, page 111. Ah, there's a tension between this paragraph: The stateful proxy MUST choose the "best" final response among those received and stored in the response context. and this one: 3-6xx responses are delivered hop-by-hop. When issuing a 3-6xx response, the element is effectively acting as a UAS, issuing its own response, usually based on the responses received from downstream elements. An element SHOULD preserve the To tag when simply forwarding a 3-6xx response to a request that did not contain a To tag. But if many implementations take "choose the best final response" to mean only re-sending the response code, we have a problem. OTOH, it's quite possible to reserve a *set* of 6xx response codes to carry the decline-type. The only allocated 6xx responses are 600 (generic), 603, 604, and 606. Dale