Subject: [Sip] ACK not matching

From: <[email-masked]>
Date: Wed, 10 Dec 2008 16:39:56 +0530

Hi,

Is it correct to have "user=phone" added only in ACK's To header while
it is missing in initial INVITE, even though both the messages use
Tel-URI.

Please refer to the trace below:

Request-Line: INVITE sip:[email-masked] SIP/2.0

    Message Header

        Via: SIP/2.0/UDP
X.X.X.X:5060;branch=z9hG4bKf0m63e30306gvdocj180.1

        To: <sip:[email-masked];transport=UDP>

        From: <sip:[email-masked];user=phone>;tag=t570lgsc

        Call-ID: 10.6.0.13450701228437693202

        CSeq: 2 INVITE

        Max-Forwards: 66

        Content-Length: 211

        Contact: <sip:[email-masked]:5060;transport=udp>

        Content-Type: application/sdp

        Allow: INVITE, ACK, CANCEL, BYE, OPTIONS, PRACK

        Accept: application/sdp

    Status-Line: SIP/2.0 100 Trying

    Message Header

        Via: SIP/2.0/UDP
X.X.X.X:5060;branch=z9hG4bKf0m63e30306gvdocj180.1

        f:<sip:[email-masked];user=phone>;tag=t570lgsc

        t:<sip:[email-masked];transport=UDP>

        i:10.6.0.13450701228437693202

        CSeq:2 INVITE

        l:0

    Status-Line: SIP/2.0 180 Ringing

    Message Header

        Via: SIP/2.0/UDP
X.X.X.X:5060;branch=z9hG4bKf0m63e30306gvdocj180.1

        f:<sip:[email-masked];user=phone>;tag=t570lgsc

t:<sip:[email-masked];transport=UDP>;tag=000000009EC7356300000
00000

        i:10.6.0.13450701228437693202

        CSeq:2 INVITE

        l:0

    Status-Line: SIP/2.0 200 OK

    Message Header

        Via: SIP/2.0/UDP
X.X.X.X:5060;branch=z9hG4bKf0m63e30306gvdocj180.1

        f:<sip:[email-masked];user=phone>;tag=t570lgsc

t:<sip:[email-masked];transport=UDP>;tag=000000009EC7356300000
00000

        i:10.6.0.13450701228437693202

        CSeq:2 INVITE

        c:application/sdp

        m:<sip:172.20.192.109:5060>

        l:203

    Request-Line: ACK sip:172.20.192.109:5060 SIP/2.0

    Message Header

        Via: SIP/2.0/UDP
X.X.X.X:5060;branch=z9hG4bKf0m63e30306gvdocj180.1

        To:
<sip:[email-masked];transport=UDP;user=phone>;tag=000000009EC7
35630000000000

        From: <sip:[email-masked];user=phone>;tag=t570lgsc

        Call-ID: 10.6.0.13450701228437693202

        CSeq: 2 ACK

        Max-Forwards: 68

        Content-Length: 0

Regards,

Sunil

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---

From: "Christer Holmberg" <[email-masked]>
Date: Wed, 10 Dec 2008 12:27:47 +0100

Hi,
 
No, user=phone should not be added. Only the To tag for the dialog,
which you get in responses, should be added to the ACK (and all other
in-dialog requests).
 
Regards,
 
Christer

________________________________

	From: [email-masked] [mailto:[email-masked]] On
Behalf Of [email-masked]
	Sent: 10. joulukuuta 2008 13:10
	To: [email-masked]
	Subject: [Sip] ACK not matching

	Hi,

	Is it correct to have "user=phone" added only in ACK's To header
while it is missing in initial INVITE, even though both the messages use
Tel-URI.

	    Message Header

	        Via: SIP/2.0/UDP

	        CSeq: 2 INVITE

	        Max-Forwards: 66

	        Content-Length: 211

	        Accept: application/sdp

	    Message Header

	        Via: SIP/2.0/UDP

	        CSeq:2 INVITE

	        l:0

	    Message Header

	        Via: SIP/2.0/UDP

	        CSeq:2 INVITE

	        l:0

	    Message Header

	        Via: SIP/2.0/UDP

	        CSeq:2 INVITE

	        c:application/sdp

	        l:203

	    Message Header

	        Via: SIP/2.0/UDP

	        To:

	        CSeq: 2 ACK

	        Max-Forwards: 68

	        Content-Length: 0

	Regards,

	Sunil

---

From: "Dale Worley" <[email-masked]>
Date: Wed, 10 Dec 2008 12:44:34 -0500

On Wed, 2008-12-10 at 16:39 +0530, [email-masked] wrote:
> Is it correct to have “user=phone” added only in ACK’s To header while

The matter is not well-settled by the standards.  RFC 3261 requires the
UAs to not change the To/From URIs in requests they generate, but it
also requires that UAs not look at the To/From URIs that they receive,
only the tags (except in certain special circumstances).

Some proposed changes and uses of SIP require the To/From URIs to be
changed.

So the current best practice is (1) Never depend on the To/From URIs in
incoming messages to be the same as in the initial INVITE, only pay
attention to the tags, and (2) Only change the To/From URIs in specific
situations where you absolutely must do so.

In this case, there is no reason why the ACK To/From URIs differ from
the INVITE values (indeed, it's hard to think of any reason it could
be), so "user=phone" should not be added.

Dale