[Spce-user] Weird situation with End2End ACKs from a carrier

Andrew Pogrebennyk apogrebennyk at sipwise.com
Tue Mar 10 04:38:53 EDT 2020

On 3/9/20 11:13 AM, Raúl Alexis Betancor Santana wrote:
> As you could see, the From on the second ACK get weird, also non RFC
> compliant and then sems refuse it and at the end, the call gets dropped.
> I've been trying to figure out what part of the proxy routing script
> it's responsible of this, but didn't find any uac_replace call or
> anything related
> This only happens on a 10:2 basis on the incoming calls ... but get
> people annoyed ... because the hear the the other end and begins their
> conversation and suddendly the call gets dropped.
> Any clue about what could be happening? ... it only happers with this
> USA based carrier, everything else works perfect.
> Its a SPCE mr7.5.3 with the latest patches ... but this happens since we
> upgraded from 5.5.1 to 7.5.3

as a rough guess what if you try to create a customtt for the file
/etc/ngcp-config/templates/etc/kamailio/proxy/kamailio.cfg.tt2 and
change only one parameter, uac restore_mode from auto:
modparam("uac", "restore_mode", "auto")
to none:
modparam("uac", "restore_mode", "none")
Does it help to solve the problem? If this doesn't help we'll need a
full PCAP to analyze.


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