Subject: [Iptel] Re: I-D ACTION:draft-rosen-iptel-dialstring-03.txt

From: "Stastny Richard" <[email-masked]>
Date: Wed, 8 Mar 2006 00:44:34 +0100

Brian,
 
in principle I support and welcome this draft
 
A minor comment to the phone-context examples:
 
"When the "user=dialstring" is used, a context parameter as defined in
   [RFC3966] MUST be specified."
 
Ok
 
but in your examples you use
(Examples of dialstring use include)
   ; what a SIP Phone might emit when a user dials extension 123
   sip:[email-masked];user=dialstring;
      phone-context='AtlantaDialPlan'
 
but phone-context is defined in RFC3966 as:
context = ";phone-context=" descriptor
descriptor = domainname / global-number-digits

this is because the phone-context must globally unique

so you should use in your examples either

phone-context=altlanta.example.com

or

phone-context=+1234

(without "")

regards

Richard

________________________________

Von: [email-masked] [mailto:[email-masked]]
Gesendet: Di 07.03.2006 21:50
An: [email-masked]
Betreff: I-D ACTION:draft-rosen-iptel-dialstring-03.txt 

A New Internet-Draft is available from the on-line Internet-Drafts directories.

        Title           : Dialstring parameter for the Session Initiation Protocol URI
        Author(s)       : B. Rosen
        Filename        : draft-rosen-iptel-dialstring-03.txt
        Pages           : 8
        Date            : 2006-3-7
       
RFC3966 explicitly states that TEL URIs may not represent a dial
string.  That leaves no way specify a dialstring in a standardized
way.  Great confusion exists with the SIP URI parameter "user=phone",
and specifically, if it can represent a dial string.  This memo
creates a new value for the user parameter "dialstring", so that one
may specify "user=dialstring" to encode a dialstring as a SIP or SIPS
URI.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-rosen-iptel-dialstring-03.txt

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From: Paul Kyzivat <[email-masked]>
Date: Wed, 08 Mar 2006 11:26:08 -0500

I agree with Richard that I support the concept of this draft, but have 
a few nits. I have a different spin on the one Richard pointed out:

All the parameters defined in 3966 are part of the phone number. When 
the definitions in 3966 are applied to sip with the user=phone uri 
parameter, the parameters defined in 3966 all go before the "@" sign. 
The user=dialstring is just a variant on this, so I expect the 
phone-context parameter ought to go before the "@" sign in that case 
too. For example:

; what a SIP Phone might emit when a user dials extension 123
sip:123;phone-context=[email-masked];user=dialstring

Next, this draft permits the dialled digits A-F, but it doesn't permit * 
and #. 3966 does permit * and # as well as E and F - apparently they are 
synonymous. (When used in conjunction with sip uris, the # has to be 
escaped as %23.)

We are slightly in limbo here, because 3261 references 2805 rather than 
3966. Need to deal with that somehow. I think it would be helpful to 
introduce in this draft a formal syntax for the user part. The following 
is a suggested start at a syntax. This could just be for 
user=dialstring, but this might be a convenient place to revise 3261 so 
it references 3966 for user=phone as well. The following is a start at 
the changes. I've included some stuff from 3261 and 3966 for reference 
that probably don't need to be included in the draft.

;;; UNCHANGED RULES FROM 3261:
;SIP-URI          =  "sip:" [ userinfo ] hostport
;                    uri-parameters [ headers ]
;SIPS-URI         =  "sips:" [ userinfo ] hostport
;                    uri-parameters [ headers ]
;user             =  1*( unreserved / escaped / user-unreserved )
;user-unreserved  =  "&" / "=" / "+" / "$" / "," / ";" / "?" / "/"
;
;uri-parameters    =  *( ";" uri-parameter)
;
;uri-parameter     =  transport-param / user-param / method-param
;                     / ttl-param / maddr-param / lr-param 

;                     / other-param

;;; UNCHANGED RULES FROM 3966
;   local-number         = local-number-digits *par context *par
;   local-number-digits  =
;      *phonedigit-hex (HEXDIG / "*" / "#")*phonedigit-hex
;   phonedigit-hex       = HEXDIG / "*" / "#" / [ visual-separator ]
;   visual-separator     = "-" / "." / "(" / ")"

;;; REVISED RULES FROM 3261
userinfo         =  ( user / telephone-subscriber / dial-string )
                     [ ":" password ] "@"
user-param        =  "user="
                         ( "phone" / "ip" / "dialstring" / other-user)

    The BNF for 'telephone-subscriber', 'par', and 'context' can be
    found in RFC 3966 [?].  Note, however, that any characters allowed
    there that are not allowed in the 'user' part of the SIP URI MUST
    be escaped.

;;; NEW RULES
dial-string = dial-string-number *par context *par
dial-string-number = 1* ( [ "X" ] 1*dial-string-segment )
dial-string-segment = ( * "P" ) dial-string-digit
dial-string-digit = HEXDIG / "*" / "#"

This needs to be accompanied by text explaining that the dial-string 
syntax applies when the user=dialstring parameter is present.

	Thanks,
	Paul

Stastny Richard wrote:
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---

From: "Brian Rosen" <[email-masked]>
Date: Wed, 8 Mar 2006 14:33:03 -0500

I think what you propose for the phone number parameters are too ugly, and
unnecessary.  What I did with the current language is define a new parameter
as defined in 3966.  This makes the user parameter and the phone-context
parameter the same type of parameter.  The user= doesn't go before the "@",
and neither should the phone-context.

I do think fixing 3261's ABNF is a good idea.  Having a formal ABNF in this
draft for the dialstring is a good idea.

I can add the escaped * and #.  

And Richard, of course you are correct; sloppy editing on my part, and I'll
fix the examples.

Brian
-----Original Message-----
From: Paul Kyzivat [mailto:[email-masked]] 
Sent: Wednesday, March 08, 2006 11:26 AM
To: [email-masked]
Cc: Stastny Richard
Subject: Re: [Iptel] Re: I-D ACTION:draft-rosen-iptel-dialstring-03.txt

; what a SIP Phone might emit when a user dials extension 123
sip:123;phone-context=[email-masked];user=dialstrin
g

;                     / other-param

;;; NEW RULES

	Thanks,
	Paul

---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 08 Mar 2006 15:44:48 -0500

> and neither should the phone-context.

It was my feeling that this is pretty similar to user=phone, so I was 
expecting the representation to be similar as well. I find it pretty 
surprising to reuse the phone-context parameter but in an entirely 
different namespace. Even more so if the values for the parameter have a 
differing meaning. (If that is to be done it might be better to change 
the name.)

Are you proposing that a phone-context *URI parameter* be valid for 
user=phone as well?

I would prefer this to deviate as little as possible from the sip form 
of the tel uri.

> I can add the escaped * and #.  

Only # *needs* to be escaped if it is used.

	Paul

>>A New Internet-Draft is available from the on-line Internet-Drafts
> 
> directories.
> 
>>
>>        Title           : Dialstring parameter for the Session Initiation
> 
> Protocol URI
> 
>>        Author(s)       : B. Rosen
>>[email-masked] with the word unsubscribe in the body of the
> 
> message. 
> 
>>Internet-Drafts are also available by anonymous FTP. Login with the
> 
> username
> 
>>        a MIME-compliant mail reader.  Different MIME-compliant mail
> 
> readers
>