The literal contact header (after subst_hf mangling) became

Which is completely bogus.

I was trying (as a temporary hack) to mangle this to become

Which would have matched the contact header from the INVITE and then I would have seen whether this affects the subsequent ACK for the 200 OK.

But my usage of subst_hf() turned this (syntactically correct yet uninterpretable) header

The code for the mangling is this:

$var(ctct) = "<sip:2018092417381900003@81.x.x.x>";
subst_hf("Contact", “/\<.+\>/$var(ctct)\r\n/", "a”);

Which is why I originally asked about how to use subst_hf just to debug the missing ACK.

On 24 Sep 2018, at 19:25, Alex Balashov <abalashov@evaristesys.com> wrote:

On Mon, Sep 24, 2018 at 06:27:51PM +0100, Ben Hood wrote:

Contact: <sip:2018092417381900003@81.x.x <sip:2018092417381900003@81.x.x>.x>

Is this literally your Contact header? If so, it is definitely not
grammatically valid, and you are entirely right to assume that the
end-to-end ACK, along with any other in-dialog messages, will not be
routed from the caller correctly.

--
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

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