>
> In testing labs I am seeing a worrying number of UA
> implementations making the same mistake of sending requests
> to a Proxy where the Request-URI is in the form
> sip:user@<proxy-address>. I think some of the confusion may
> be traced back to early SIP message flows which showed this
> behaviour. I urge implementers to rectify this situation as
> we are seeing this cause a great deal of confusion to
> the first commercial adopters of SIP technology. These people
> are not SIP protocol experts and just expect this technology
> to work.
>
> It is often seen when using a local out bound proxy. The
> situation is that the UA takes a configuration parameter
> for the local proxy. You can then dial by keying in just the
> user part of a SIP URL. The UA then builds a complete URL by
> adding the Proxy's address and sends the message to the proxy.
> The Proxy then receives an INVITE of the form
> sip:user@proxy-ip - according to the protocol spec the Proxy
> will route this request to the server at the given IP address.
> This is obviously itself so an illegal loop is created. A
I disagree, if the uri points to proxyA, that only implies that
proxyA has access to a location service that can forward this
request (at least 1 hop closer) to 'user'
> simple solution would appear to be to configure these UAs with
> a 'default dial domain' and for it to build URLs using this
> not the Proxy's address.
Sure, but since the proxy is probably linked to the local domain
anyway, I think it's more realistic to configure the proxy with
a 'default dial domain' than force it on every UA that happens to
wander in.
After all, isn't that what proxies are for ? Otherwise, the UA
might as well send the invite directly to the destination.
david
> Cheers,
> Neil.
> --
> Ubiquity Software Corporation, UK http://www.ubiquity.net
>
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