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RFC 4028, "Session Timers in the Session Initiation Protocol (SIP)", April 2005

Source of RFC: sip (rai)

Errata ID: 1681
Status: Verified
Type: Technical
Publication Format(s) : TEXT

Reported By: Muthu Arul Mozhi
Date Reported: 2009-02-09
Verifier Name: Robert Sparks
Date Verified: 2010-04-03

Section 13 says:

In section 13 (Example Call Flow) the From tag never changes 
between the initial INVITE message and the subsequent INVITE 
messages sent after receiving a 422:

message 1
   INVITE sips:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds8
   Supported: timer
   Session-Expires: 50
   Max-Forwards: 70
   To: Bob <sips:bob@biloxi.example.com>
   From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
   Call-ID: a84b4c76e66710
   CSeq: 314159 INVITE
   Contact: <sips:alice@pc33.atlanta.example.com>
   Content-Type: application/sdp
   Content-Length: 142

message 4
   INVITE sips:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds9
   Supported: timer
   Session-Expires: 3600
   Min-SE: 3600
   Max-Forwards: 70
   To: Bob <sips:bob@biloxi.example.com>
   From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
   Call-ID: a84b4c76e66710
   CSeq: 314160 INVITE
   Contact: <sips:alice@pc33.atlanta.example.com>
   Content-Type: application/sdp
   Content-Length: 142

message 10
   INVITE sips:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds10
   Supported: timer
   Session-Expires: 4000
   Min-SE: 4000
   Max-Forwards: 70
   To: Bob <sips:bob@biloxi.example.com>
   From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
   Call-ID: a84b4c76e66710
   CSeq: 314161 INVITE
   Contact: <sips:alice@pc33.atlanta.example.com>
   Content-Type: application/sdp

However, as per RFC 3261, if an initial INVITE generates a non-2xx final
response, that terminates all sessions and all dialogs that were created. 

Hence, these are not re-INVITE messages, rather new INVITE messages and 
should use a new From tag.

It should say:

message 1
   INVITE sips:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds8
   Supported: timer
   Session-Expires: 50
   Max-Forwards: 70
   To: Bob <sips:bob@biloxi.example.com>
   From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
   Call-ID: a84b4c76e66710
   CSeq: 314159 INVITE
   Contact: <sips:alice@pc33.atlanta.example.com>
   Content-Type: application/sdp
   Content-Length: 142

message 4
   INVITE sips:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds9
   Supported: timer
   Session-Expires: 3600
   Min-SE: 3600
   Max-Forwards: 70
   To: Bob <sips:bob@biloxi.example.com>
   From: Alice <sips:alice@atlanta.example.com>;tag=2568701785
   Call-ID: a84b4c76e66710
   CSeq: 314160 INVITE
   Contact: <sips:alice@pc33.atlanta.example.com>
   Content-Type: application/sdp
   Content-Length: 142

message 10
   INVITE sips:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bKnashds10
   Supported: timer
   Session-Expires: 4000
   Min-SE: 4000
   Max-Forwards: 70
   To: Bob <sips:bob@biloxi.example.com>
   From: Alice <sips:alice@atlanta.example.com>;tag=5647301796
   Call-ID: a84b4c76e66710
   CSeq: 314161 INVITE
   Contact: <sips:alice@pc33.atlanta.example.com>
   Content-Type: application/sdp

Notes:

-----Original Message-----
From: Paul Kyzivat (pkyzivat)
Sent: Monday, February 09, 2009 10:09 PM
To: Muthu ArulMozhi Perumal (mperumal)
Cc: Radha Krishna Saragadam (rsaragad); Jonathan Rosenberg (jdrosen); Ram Mohan R (rmohanr)
Subject: Re: UAS behavior after sending 422 for initial INVITE

yes, I think so.

Paul

Muthu ArulMozhi Perumal (mperumal) wrote:
> In section 13 (Example Call Flow) of RFC 4028 the From tag never changes
> between the initial INVITE message and the subsequent INVITE messages
> sent after receiving a 422:
>
> message 1
> INVITE sips:bob@biloxi.example.com SIP/2.0
> From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
> Call-ID: a84b4c76e66710
>
> message 4
> INVITE sips:bob@biloxi.example.com SIP/2.0
> From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
> Call-ID: a84b4c76e66710
>
> message 10
> INVITE sips:bob@biloxi.example.com SIP/2.0
> From: Alice <sips:alice@atlanta.example.com>;tag=1928301774
> Call-ID: a84b4c76e66710
>
> Is this a bug in the RFC?
>
> thanks,
> Muthu
>
> |-----Original Message-----
> |From: Paul Kyzivat (pkyzivat)
> |Sent: Wednesday, February 04, 2009 12:36 AM
> |To: Radha Krishna Saragadam (rsaragad)
> |Cc: Jonathan Rosenberg (jdrosen); Muthu ArulMozhi Perumal (mperumal);
> Ram Mohan R (rmohanr)
> |Subject: Re: UAS behavior after sending 422 for initial INVITE
> |
> |Radha,
> |
> |It is not a reinvite, because a dialog was never established - the
> first
> |call failed.
> |
> |So you are starting a new invite. You can use the same callid, but
> |should use a new from-tag.
> |
> | Thanks,
> | Paul
> |
> |Radha Krishna Saragadam (rsaragad) wrote:
> |> Hi Paul
> |>
> |> My question is for initial INVITE. For initial INVITE if UA
> |> receives 422 and UA want to retry INVITE with new value increased
> value
> |> then what should be the To(with tag), From(with tag) and CallID
> values?
> |> Is it a Re-INVITE or new a Dialog? Section 7.3 says same value for
> |> To,From and CallID
> |>
> |> Regards
> |> S.Radha krishna

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