07:59:23.572319 IP *my.kamailio.server*.46245 > *ms.teams.server*.sip-tls: Flags [P.], seq 1:518, ack 1, win 502, length 517

07:59:23.802458 IP *ms.teams.server*.sip-tls > *my.kamailio.server*.46245: Flags [P.], seq 1:3767, ack 518, win 2051, length 3766

The TLS connection shows as successful in the logs.

- Charles

Date: Thu, 7 Jan 2021 19:12:10 -0800
From: Joel Serrano <joel@textplus.com>
To: "Kamailio (SER) - Users Mailing List"
<sr-users@lists.kamailio.org>
Subject: Re: [SR-Users] Source Port on TLS OPTIONS from Dispatcher
Message-ID:
<CAMtXxQnLtEyD=40cwKembxiyj3D778eK=+5JD7sL4CvYbYXF1g@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Hi Charles,

I don't think your issue is rport, make sure you are setting the Contact
header correctly.

Have you checked this blog post:
https://skalatan.de/en/blog/kamailio-sbc-teams ?

There is a specific section that talks about how to tell Kamailio to send
the OPTIONS like MS Teams wants them.

Good luck,
Joel.

On Jan 7, 2021, at 7:31 PM, Charles Phillips <charles@rustybike.com> wrote:

Hello all. As they say in radio, “long time listener, first time caller”

Anyway, I am having trouble getting past the following road block and any help would be greatly appreciated.

Kamailio version is 5.4.3

When attempting to use dispatcher to send OPTIONS packets to several TLS destinations, the packets are leaving the Kamailio server on random ports. This is a problem because the servers I am sending the OPTIONS to (MS Teams) are enforcing rport so the responses are returned to a port that Kamailio is not listening on. I have tried to force the socket in the event route (relevant parts of snippet below) but it does not appear to help. I should also mention that I am not behind NAT and the TLS socket is specified in the dispatcher attrs.

event_route[tm:local-request] {
sip_trace();

$fs = “tls:**ip-address**:5061”;

}

I have used Kamailio as a TLS server for many projects, but this is my first time as a client. I am sure I am missing something.

- Charles