Re: [SIP] phone-context and RFC2543bis

[Alan Johnston <[e-mail]>]

Will do - look for a draft shortly.

Alan

Dean Willis wrote:

> Alan,
>
> I believe the existing SIP syntax allows for arbitrary URI parameters, so
> there really aren't any syntactic changes needed.  The real question is the
> semantics. I don't believe the semantics of which you want to use
> "phone-contet" for have been discussed on the list.
>
> I'd suggest you write your thoughts up as an ID and share them with us. I
> think the basic idea sounds pretty good, but I'd like to see a more complete
> framing of your intent.
>
> --
> Dean
>
> > -----Original Message-----
> > From: [e-mail]
> > [mailto:[e-mail]]On Behalf Of Alan Johnston
> > Sent: Friday, April 07, 2000 10:52 AM
> > To: SIP
> > Subject: [SIP] phone-context and RFC2543bis
> >
> >
> > Based on reports from Adelaide, it sounds like the consensus of
> > the working
> > group was to progress the Call Flows I-D
> > (draft-ietf-sip-call-flows-00.txt) to
> > Informational RFC as soon as possible.
> >
> > One item that needs to be resolved first is the "phone-context"
> > tag which is
> > used extensively in the Gateway dialing sections of the document
> > for private
> > phone numbers (extensions).
> >
> > In RFC2543, support for phone numbers in SIP URLs was included by
> > including
> > parameters from the then current version of the Tel URL I-D if
> > "user=phone" was
> > present.  Since then, there have been additional drafts of this document
> > (currently draft-antti-telephony-url-12.txt).
> >
> > One of the critical additions to the Tel draft since RFC2543 was
> > the addition of
> > the phone-context tag used for local numbers to identify the
> > scope in which the
> > number is valid.  I believe this tag needs to be included in SIP
> > URLs in the
> > next SIP draft.
> >
> > For example, the U.S. directory assistance telephone number can
> > be written in
> > global form as:
> >
> >       sip:[e-mail];user=phone
> >
> > However, if the number was only valid if dialed from within the
> > U.S., the number
> > could be written as a local phone number as:
> >
> >       sip:[e-mail];phone-context=+1
> >
> > Where the phone-context tag indicates that it is only valid from
> > within country
> > code 1.
> >
> > Another more compelling use of the phone-context tag is in
> > dealing with private
> > numbers - numbers that are not part of the public number space,
> > but are part of
> > a private numbering plan administered by a corporation or
> > organization.  The
> > examples in the Call Flows document are of this kind:
> >
> >       sip:[e-mail];phone-context=mycarrier
> >
> > In this example, it appears that the host portion (gateway
> > address) of the URL
> > is sufficient to specify the context of the private number.
> > However, for cases
> > where a gateway is shared among multiple customers, each with possibly
> > overlapping private numbering plans, the use of phone-context is required:
> >       sip:[e-mail];phone-context=mycarrier-customer1
> >
> > The use of the phone-context tag also allows interdomain private dialing,
> > something impossible in todays PSTN.  For example, dialed digits for a
> > particular dialing plan could be sent to a proxy for gateway lookup
> >
> >       sip:[e-mail];phone-context=carrier-customer2
> >
> > The proxy would lookup the gateway based on dialed digits and
> > phone-context.  If
> > the proxy did not have gateway information for that carrier (domain), the
> > request could be proxied to that domain with the Request-URI becoming:
> >
> >       sip:[e-mail];phone-context=carrier-customer2
> >
> > These are just a few examples of the use of this tag.
> >
> > Are there any reasons why this tag should not be supported in SIP
> > URLs in the
> > next draft of RFC2543?
> >
> > Alan Johnston
> > MCI WorldCom
> >
> >
> >
> > _______________________________________________
> > SIP mailing list
> > [e-mail]
> > http://lists.bell-labs.com/mailman/listinfo/sip
> >






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