> Without a specific spec or a RFC, its hard to 
> tell who is right and who should change.

My understanding of RFC 3261 (and RFC 2543) is that user=phone indicates that 
the user portion can be decoded as a telephone-subscriber.  However, RFC 3261 
is too vague concerning the topic.  It indicates to set user=phone when adding 
telephone-subscriber without explicitly indicating that it is the only use of 
user=phone.

Thus some vendors interpret user=phone as though it doesn't imply that the user 
can be decoded as a telephone-subscriber.  However, I disagree with this 
interpretation because it means that nothing indicates that the user portion 
can be decoded as telephone-subscriber.  Since "user URI parameter exists to 
distinguish telephone numbers from user names that happen to look like 
telephone numbers", I find it strange to include user=phone to indicate that 
"anonymous" or "" are telephone numbers.

RFC 3261 section 19.1.1:

"The set of valid telephone-subscriber strings is a subset of
 valid user strings.  The user URI parameter exists to
 distinguish telephone numbers from user names that happen to
 look like telephone numbers.  If the user string contains a
 telephone number formatted as a telephone-subscriber, the user
 parameter value "phone" SHOULD be present.  Even without this
 parameter, recipients of SIP and SIPS URIs MAY interpret the
 pre-@ part as a telephone number if local restrictions on the
 name space for user name allow it."

> ----- Original Message -----
> From: Brett Tate <[email protected]>
> To: Vivek Singla <[email protected]>; "Sip-
> [email protected]" <Sip-
> [email protected]>
> Cc:
> Sent: Friday, February 1, 2013 12:57 PM
> Subject: RE: [Sip-implementors] Any RFC reference for "user=phone" in
> case of an Anonymous From header
> 
> Unfortunately, RFC 3261 is underspecified concerning the user=phone
> topic and sipcore doesn't seem to want to fix the issue.  Thus do
> whatever you want. :)
> 
> The following link is to one of the replies that I received concerning
> the topic.
> 
> http://www.ietf.org/mail-archive/web/sipcore/current/msg01784.html
> 
> 
> Some vendors will not like receiving a user=phone when the user portion
> of sip-uri is missing or does not decode as a telephone-subscriber per
> RFC 3966 (or RFC 2806).
> 
> Anonymous examples can be found within RFC 3261, RFC 3323, and RFC
> 3325.  They do not include user=phone.


_______________________________________________
Sip-implementors mailing list
[email protected]
https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors

Reply via email to