2010/10/21 Juha Heinanen jh@tutpro.com:
rfc3261 allows that the ua is configured with address of registrar. in fact, there are sip UAs that allow configuring registrar differently from proxy.
Yes, but isn't nicer provisioning a UA just with AoR, password and domain letting DNS NAPTR/SRV and routing in the proxy to do their magic? :)
if proxy happens to know about registrar or some presence events, it is good luck. you cannot assume it.
Typically if a provider offers presence service its proxy should be ready for that.