Re: MMUSIC+PINT joint WG Last Call

[Jonathan Rosenberg <[e-mail]>]

Igor Faynberg wrote:
> 
> MMUSIC and PINT participants:
> 
> Following the advice of Transport Area Directors, this is to announce a
> 
> WG last call on 'draft-antti-telephony-url-09.txt'. The document is
> ------------     --------------------------------
> to be reviewed by both groups on a subject of becoming PROPOSED
> 
> STANDARD by September 7,1999.

Two comments:

1. The draft has a very particular usage for these URL's in mind. The
basic idea is that a user "receiving" this URL would directly dial the
number indicated. In fact, from the document itself:

> These URL schemes are used to direct the user agent to place a call
>    using the telephone network. The network in question may be a


It is for this reason that post dial sequences, for example, make
perfect sense. However, in the usage envisioned in SIP (perhaps others
see it used differently), the tel URL would identify a GSTN subscriber,
be included in the request URI and To field of the INVITE, and sent to
some local proxy. THe proxy, using enum and/or GLP, translates this to a
full SIP URL, so it can route the request. This SIP URL is then placed
in the request URI. In this case, the URI is used to identify the
resource, rather than indicate the means to dial a number to contact it.
In this usage, including things like post dial sequences just doesn't
make sense, since the original user of the tel URL is never actually
going to dial the number. Thus, perhaps some kind of rewording softening
this usage would be nice.

2. One of the things that came up at the last meeting from the DCS
documents was a proposal to add some values to the user parameter in the
SIP URL. Right now, SIP allows user=ip and user=phone. The suggestion
was to add user=lnp-phone and user=private. It seems that two of these
make a lot of sense for the tel URL. In particular, it seems highly
desirable to know whether a tel URL represents a number that has already
been translated, as is the purpose of the user=lnp-phone parameter. This
makes sense when one considers that tel URL's might be used in places
like megaco (?) as well. Its not useful when the application of the tel
URL is restricted to indicating a number a user should dial, but makes
more sense in broader applications like SIP/megaco integration with SS7
(see my point above).

Thanks,
Jonathan R.
-- 
Jonathan D. Rosenberg                       Lucent Technologies
Member of Technical Staff                   101 Crawfords Corner Rd.
High Speed Networks Research                Holmdel, NJ 07733
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URL: http://www.cs.columbia.edu/~jdrosen