Subject: RE: AW: AW: [Sip] SIPIT Interop problem with ;user=phone

From: "Rosen, Brian" <[email-masked]>
Date: Tue, 2 Sep 2003 11:01:03 -0400

> He dials +3584012345. How does the UA know if it should 
> append @nokia.com and make it a sip URI or just make it a tel URI?
By definition, if the UA does not know how to translate
dial strings to phone numbers, it MUST use a sip uri.  There
is no option to use a tel uri.

I think your example not ideal only because a UA could
have a trivial rule that a number starting with + is known to
be a globally dialable number, and thus COULD be put in a tel
uri.  However, I would hope that phones did not do a lot of
guessing; if they have knowledge of the local dialing plan and
special dialing options, then they should interpret the dial
string and do the right thing.  If they don't they should put
the dial string in a sip uri and let a proxy figure it out.

> 
> Options (if the user indicated its choice)
> - The dialled digits placed in a tel URI with a phone-context.
This cannot work because the dial string may not be a phone number,
and thus this would not be in conformance with 2806bis.

> - If the UA does not have a routing table and cannot place a 
> phone-context, then it needs to place the dialled digits in a 
> sip URI. But I believe it should indicate the user as a dial 
> string (as you suggest). 
I agree.
....snip
> 
> - If the user dials county code and area code (3584012345), 
> the dialled digits placed in a tel URI with no phone-context.
This is only possible if the phone understands the local dialing
plan.  Otherwise, it is not in a position to know what a "country
code" and "area code" are. whether they are present, or in fact
if this string of digits is actually a phone number at all.

> 
> I agree this is too complicated for the user. So what do we 
> do to make life easier for the end users? Should we give the 
> freedom to the user to just enter digits and we need to 
> technically figure out what his intension is?
Either the phone does it, or a proxy does it.  The mechanism isn't
very complicated either way, but since it seems clear that not
all phones will do it themselves, we need mechanisms in proxies to
offer the service.  They need a way to know that it should be
invoked.  It may be possible to deduce it, but I'd prefer to make
it explicit.

Brian 

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---

From: Juha Heinanen <[email-masked]>
Date: Tue, 2 Sep 2003 19:54:41 +0300

Rosen, Brian writes:

 > uri.  

no matter what number the user dials (with or without +), my sip phone
will do the same thing:  append its own domain to the number and forward
the call to the proxy of the domain.  the proxy of the phone's domain
will then interpret the number according to the conventions that exist
within the domain.

-- juha