Re: How to correctly generate a 181 Call is being forwarded reply?

Hello,

Sorry, but I don't fully understand the problem here. According to RFC 3161 the 181 replies need to have a To-tag.

According to RFC 5359 the To-Tag has a different value as later then used e.g. in the 200 OK confirmation.

The loose_route function usually doesn't check for transactions, as already pointed out, but checks for Route header.

So, if your later INVITE with a To-Tag don't work, you probably should investigate why the routing information is missing in the second INVITE, or add a special handling for re-INVITEs to your cfg when there is no routing information.

Cheers,

Henning 

> -----Original Message-----
> From: Benoit Panizzon via sr-users <[email protected]>
> Sent: Montag, 1. Dezember 2025 15:14
> To: Benoit Panizzon via sr-users <[email protected]>
> Cc: Benoit Panizzon <[email protected]>
> Subject: [SR-Users] Re: How to correctly generate a 181 Call is being
> forwarded reply?
> 
> Hi again
> 
> > I don't seem to get it working as expected - still trying to figure out
> > what and where the call fails.
> 
> I think I have found what goes wrong.
> 
> A => B => CFW => C
> 
> C has MIN-SE: 900
> A is initially sending Sestion-Timer: 600
> 
> Without 181 reply:
> 
> C replies with 422 Timer too Small Min-SE: 900
> This 422 Reply has a ToTag.
> 
> A re-initiates the call with a larger session timer, that INVITE has NO
> ToTag - new transaction. The Calls succeeds.
> 
> Now I repeat the same, but I send a 181 message back to A BEFORE A
> receives the 422 from C. That 181 has a ToTag.
> 
> Now when A re-initiates the INVITE, it includes the ToTag received in
> the 181 and loose_route fails as there is no such transaction.
> 
> Is A misbehaving by including a ToTag when it should not? Should the 181
> reply not contain a ToTag?
> 
> I again tried all variants
> 
> * sl_send_reply() generates ToTag
> * send_reply() generates ToTag
> * t_reply() does not send the reply.
> 
> Mit freundlichen Grüssen
> 
> -Benoît Panizzon-
> --
> I m p r o W a r e   A G    -    Leiter Commerce Kunden
> ______________________________________________________
> 
> Zurlindenstrasse 29             Tel  +41 61 826 93 00
> CH-4133 Pratteln                Fax  +41 61 826 93 01
> Schweiz                         Web  http://www.imp.ch
> ______________________________________________________
> __________________________________________________________
> Kamailio - Users Mailing List - Non Commercial Discussions -- sr-
> [email protected]
> To unsubscribe send an email to [email protected]
> Important: keep the mailing list in the recipients, do not reply only to the
> sender!
__________________________________________________________
Kamailio - Users Mailing List - Non Commercial Discussions -- [email protected]
To unsubscribe send an email to [email protected]
Important: keep the mailing list in the recipients, do not reply only to the sender!