[Spce-user] Masked contact parameter 'ngcpct' missing

[Marc Storck]

Good morning,

I have noticed an issue with calls to "voiceboxpass" from a VoIP peer.

In our case, after the call is answered by  the NGCP Asterisk, kamailio-lb sends a SIP 200 OK to the VoIP peer with the following contact he

Contact: <sip:ngcp-lb at a.b.c.d:5060;ngcpct=7369703a3132372e302e302e313a35303830>

The returned SIP ACK does not contain a contact header field at all, and kamailio-lb logs the line:

Masked contact parameter 'ngcpct' missing, trying fallback to 'sip:sems at 127.0.0.1:5080' - R=sip:ngcp-lb at a.b.c.d ID=2936446182-25278 at SVIGateway

As far as I can see, the ACK is forwarded to the kamailio-proxy running on port 5062, however no packet is forwarded to the asterisk server on port 5070.

Kamailio-proxy logs:

New request - M=ACK R=sip:sems at 127.0.0.1:5080 F=sip:1234567890 at a.b.c.d T=sip:did-of-voiceboxpass at w.x.y.z IP=a.b.c.d:5060 (127.0.0.1:5060) ID=2936446182-25278 at SVIGateway

As the SIP ACK never reaches the NGCP Asterisk server, the Audio Stream is terminated after 16 seconds.

The missing Contact header in the SIP ACK message does not cause any issues when calling a subscriber or a conference.

Is there something that can be done to fix the access to the NGCP Asterisk server?

Regards

Marc Storck
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