[Serusers] 305 Use Proxy

[Nils Ohlmeier]

Hi Rick,

> 	(Nils: Thanks for your helpful reply.)
>
>> unfortunately the usage of 305 is totally under specified. And I haven't
>> it being used in the field ever. Anybody else maybe?
>
> There are good reasons for using it though.  For me, these are:
>
> 1. I want to pass off any POTS calls to upstream SIP providers without
>    having to worry about RTP proxies (setting them up, or wondering if
>    they would be needed at all).  If traffic goes through an outside-NAT
>    proxy, the sip2pots provider would probably decide no RTP proxy is
>    needed.
>
> 2. I want to avoid being responsible for the traffic that I pass on.
>    This means that I can be a proxy to unregistered users, if they like.
>    It makes it very easy for them to try out a service if they only have
>    to set the "proxy" field in their phone.
>
> I understand that all this reasoning won't help to improve the RFC, as
> this
> is not the task of the people on this list.  I just wanted to clear up why
> this is useful (to me at least).

sure, I totally agree that there are good use-cases for this response. But
the problem seems to me that you will have to teach every SIP element in
your setup how to treat this response correctly (like you expearienced
already with your Grandstream phone). Good luck with that. And I would be
really interested if you make progress on that front.
BTW there were some discussion about this response on the IETF mailing
list several years ago. But they somehow died.

Regards
  Nils Ohlmeier
  VoIP Freelancer