[OpenSIPS-Users] fr_timeout CANCEL message sent to timed out dispatcher endpoint IP

[John Quick]

Ben,

Yes, you're right. Section 9.1 of RFC3261 says "If no provisional response
has been received, the CANCEL request MUST NOT be sent"

So then it is a question the developers will need to answer, although from a
practical point of view I doubt that it would cause a problem for the
reasons I gave.

John Quick
Smartvox Limited

> From: Ben Newlin <Ben.Newlin at genesys.com> 
> Sent: 30 June 2021 16:25
> To: john.quick at smartvox.co.uk; OpenSIPS users mailling list
<users at lists.opensips.org>
> Cc: solarman at one-n.co.uk
> Subject: Re: [OpenSIPS-Users] fr_timeout CANCEL message sent to timed out
dispatcher endpoint IP
>
> I'm pretty sure the RFCs state that a CANCEL should only be sent if some
response, usually 100 Trying, has been received. This is to avoid the
possibility of the INVITE and CANCEL > being received out of order at the
destination.
>
> Ben Newlin