[SR-Users] uac_replace_from/to, msg_apply_changes and Re-INVITE

Henning Westerholt hw at kamailio.org
Tue Mar 26 08:13:20 CET 2019


Am Dienstag, 26. März 2019, 02:27:17 CET schrieb Daniel-Constantin Mierla:
> > I am currently debugging a strange issue related to the usage of
> > uac_replace_from/to() after msg_apply_changes(). It works all fine, but in
> > a Re-INVITE case it inserts the wrong headers for the 100 - Trying case.
> > The calle
> 
> did you mean caller or callee? What side is sending the re-INVITE with
> the troubles?
> 
> Is uac using the record-route param to store the info about From/To? Or
> is via dialog variables?

Hi Daniel,

storage is with dialog variables, but in the 100 - Trying case this is 
internally done with the uac TM callbacks (If I understood the code 
correctly). If I remove the msg_apply_changes() in the Re-INVITE case, all 
works fine.

Call flow (A is a SIP client, B a PSTN destination):

A -> B INVITE, 100, 18x, 200, ACK: all fine
A -> B first Re-INVITE, 100: the 100 - Trying is broken
A -> B second Re-INVINTE, 100: the 100 - Trying is broken
... more Re-INVINTEs 
A -> B BYE: all fine

I have attached a trace, see below the 100 - Trying examples:

This is ok:

    Kamailio-IP.sip > A-SIDE-IP.na-localise: SIP, length: 405
        SIP/2.0 100 trying -- your call is important to us
        Via: SIP/2.0/UDP A-SIDE-IP:
5062;rport=5062;branch=z9hG4bKPjh2a4HyDf1ApI7kWK5ShgL7I7w9.LvoeI;received=A-
SIDE-IP
        From: sip:A-Number at Kamailio-IP;tag=Ho4cXwV4Q-LBW0n4guPOQwvi6GbiylqO
        To: sip:B-Number at Kamailio-IP
        Call-ID: po-DL6LvwksnKK56D3lF8HB4wwo6F.GS
        CSeq: 6764 INVITE
        Server: Carrier-Name SIP Voice Gateway
        Content-Length: 0

This is not OK:

12:42:59.336930 IP (tos 0x10, ttl 64, id 61398, offset 0, flags [none], proto 
UDP (17), length 461)
    Kamailio-IP.sip > A-SIDE-IP.na-localise: SIP, length: 433
        SIP/2.0 100 trying -- your call is important to us
        Via: SIP/2.0/UDP A-SIDE-IP:5062;rport=5062;branch=z9hG4bKPj3jfO6Fuk5-
SJQ2EXOIEeYJk1amH.xKvp;received=A-SIDE-IP
        From: sip:+Rewritten-Number at sip.voice.Carrier-Name.net;tag=Ho4cXwV4Q-
LBW0n4guPOQwvi6GbiylqO
        To: sip:+B-Number at Carrier-IP:5060;tag=7N2BS4K70tZ9Q
        Call-ID: po-DL6LvwksnKK56D3lF8HB4wwo6F.GS
        CSeq: 6765 INVITE
        Server: Carrier-Name SIP Voice Gateway
        Content-Length: 0

Cheers,

Henning


-- 
Henning Westerholt - https://skalatan.de/blog/
Kamailio services - https://skalatan.de/services
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