Attila Sipos wrote:
> So this leads me to another question:
>
> What is the practical difference between:
> sip:+12345...@domain.org;user=phone
> and
> sip:+12345...@anotherdomain.org;user=phone
and
tel:+12345678
> ?
>
> Is it that in the first case, the request gets sent to "domain.org"
> but in the seconds case, it is sent to "anotherdomain.org"?
>
> Are there any other differences?
That is the difference.
And the third case can be sent anywhere (and via any protocol) that gets
to the place that a pstn call to that number would get.
> Am I right that both requests should get sent to +12345678 on the PSTN?
Not necessarily. Once the request gets to the domain, its the server at
that domain that decides what happens next. It is under no formal
obligation to send it to the pstn, or to a place that also receives pstn
calls to that number, though that is a common expectation.
This is especially notable if the number is not a pstn number that the
domain is responsible for. In that case it might accept and forward it,
or it might reject it. This property is a distinct disadvantage of the
sip uri. For instance,
- you send an invite to sip:+12345...@domain.org;user=phone.
- When it gets there, the owner of that phone has set up
forwarding to his mobile phone. This causes a redirect to
sip:+13456...@domain.org;user=phone.
- you (from outside domain.org) send another invite to
sip:+13456...@domain.org;user=phone.
- when this reaches domain.org, it decides its not forwarding
calls out of its domain (to the cell provider) on behalf
of callers outside its own domain, so it returns a 404
response. (Or pick the error of your choice.)
- now you have to pick up the pieces and decide what to do.
If the 3xx had been to tel:+13456789 then it would have been clear that
it was your problem to find a path there.
I guess the "normal" fixup for something like this is for an SBC to
patch the URL in the 3xx. But I don't know what it should patch it to.
Thanks,
Paul
An advantage of the sip form is that
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