Francois,
I agree with your point entirely.
BUT, even if I choose to advertise a sip URI (with user=phone), some of
the UASs I call may well display only the numeric portion as the
callerid. Those people in turn may then attempt to call me back using a
TEL URI, and as a result, may end up going over the PSTN, even if
originating from a sip device. (I don't know how often a PSTN path will
be chosen even if a sip path was possible, but probably more often than
we would wish.)
If the devices are half way smart, even if they only show the number
they will keep the entire URI in their call log, so that if I attempt a
callback via the call log it will use the whole URI. But I expect some
devices will be dumber than that.
I don't know that we can do anything about it, except perhaps publish
some best practices drafts. But I expect it may be a problem for a long
time.
Paul
Francois Audet wrote:
> I'm still not sure I get it.
>
> If I present a Tel URI, and somebody uses it to reach me, and it just happens
> that we are both using SIP as our default "Telephony" client, then sure, you
> absolutely will be able to do whatever you want (IM, HD, etc.).
>
> The point is that if you choose to advertise a Tel URI INSTEAD of a SIP URI,
> don't be
> surprised if you have people reaching you with PSTN-capabilies only.
>
> Conversely, if you choose to advertize a SIP URI ONLY, then you may be
> missing out
> entirely on people calling from PSTN.
>
> - At least, that's the theory...
>
>> -----Original Message-----
>> From: Dan Wing [mailto:[EMAIL PROTECTED]
>> Sent: Wednesday, April 09, 2008 21:20
>> To: Audet, Francois (SC100:3055)
>> Cc: [email protected]; 'Paul Kyzivat'; 'Juha Heinanen'
>> Subject: RE: [Sip] E.164 - who owns it
>>
>>
>>
>>> -----Original Message-----
>>> From: Francois Audet [mailto:[EMAIL PROTECTED]
>>> Sent: Wednesday, April 09, 2008 8:04 PM
>>> To: Dan Wing
>>> Cc: [email protected]; Paul Kyzivat; Juha Heinanen
>>> Subject: RE: [Sip] E.164 - who owns it
>>>
>>> Well, you can still do video over PSTN with H.320. I still
>> view this
>>> as "telephony".
>> Sorry -- please pick something you cannot do over the PSTN.
>> Instant Messaging, presence, high-quality video (HDTV), whatever.
>>
>>> Not sure I understand the question.
>> Let me reword my previous email into a question:
>>
>> If you have a non-SIP telephony application that trunks
>> towards the PSTN, and it is configured to process tel URIs,
>> and it is asked to initiate a call that exceeds the
>> capabilities of the PSTN (instant messaging, presence,
>> HDTV-quality video, whatever you prefer) -- would it route
>> the call towards a "SIP trunk" in order to gain the ability
>> to set up that call, abort the call, or just ignore it all
>> and trunk towards the PSTN?
>>
>> An additional question (statement, actually) is: We can't
>> influence how that non-SIP telephony application provides for
>> its own identity and authentication of tel URIs.
>>
>> (This is getting me to lean more towards my email-identity
>> straw-man. With it, we can step out of this festering,
>> smelly pile of trying to get E.164 working well with SIP and
>> move to email-style SIP URIs. The IETF is capable of
>> building an end-to-end identity/authentication solution
>> around email-style SIP URIs; we have one (RFC4474) that works
>> if we prohibit SBCs and B2BUAs from modifying SDP).
>>
>> -d
>>
>>
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