Hi, I'm connecting Teams with kamailio server. From Kamailio to teams I have no problems, but from teams to Kamailio yes. Drop the call..

With ngrep I see that:

INVITE sip:1005@CLIENT_IP:55766;transport=UDP;rinstance=d47edf336726e940 SIP/2.0.
Record-Route: <sip:FQND_IP;r2=on;lr>.
Record-Route: <sip:FQND_IP:5061;transport=tls;r2=on;lr>.
FROM: "Javier Gonz..lez Mu..oz"<sip:+324@sip.pstnhub.microsoft.com:5061;user=phone>;tag=c17bb1eb7f8649d4a89d8d4a876ac32b.
TO: <sip:+34560@FQND:5061;user=phone>.
CSEQ: 1 INVITE.
CALL-ID: c1364913e582553a9a9c2544c3583b0a.
MAX-FORWARDS: 69.
Via: SIP/2.0/UDP 92.222.217.64;branch=z9hG4bK7bb5.0fbae76a37829205e04279f220a26af2.0;i=a1.
VIA: SIP/2.0/TLS 52.114.76.76:5061;branch=z9hG4bKd216a55.
RECORD-ROUTE: <sip:sip-du-a-eu.pstnhub.microsoft.com:5061;transport=tls;lr>.
CONTACT: <sip:api-du-a-euno.pstnhub.microsoft.com:443;x-i=b0b53fc5-76ef-4619-9a68-13e0a4eea92d;x-c=c1364913e582553a9a9c2544c3583b0a/d/8/6c25eb3789a14bf188ce6b05b5e27891>.
CONTENT-LENGTH: 1091.
MIN-SE: 300.
SUPPORTED: timer.
USER-AGENT: Microsoft.PSTNHub.SIPProxy v.2020.7.31.1 i.EUNO.0.
CONTENT-TYPE: application/sdp.
ALLOW: INVITE,ACK,OPTIONS,CANCEL,BYE,NOTIFY.
P-ASSERTED-IDENTITY: <tel:+324>,<sip:EMAIL>.
PRIVACY: id.
SESSION-EXPIRES: 3600.
.
v=0.
o=- 165103 0 IN IP4 127.0.0.1.
s=session.
c=IN IP4 52.113.44.8.
b=CT:10000000.
t=0 0.
m=audio 50452 RTP/SAVP 104 9 103 111 18 0 8 97 101 13 118.
c=IN IP4 52.113.44.8.
a=rtcp:50453.
a=ice-ufrag:FZTb.
a=ice-pwd:yD3P7nr+xNq0VYdv7xpB1F+Y.
a=rtcp-mux.
a=candidate:1 1 UDP 2130706431 52.113.44.8 50452 typ srflx raddr 10.0.33.240 rport 50

U CLIENT_IP:55766 -> FQND_IP:5060 #2
SIP/2.0 180 Ringing.
Via: SIP/2.0/UDP FQND_IP;branch=z9hG4bK7bb5.0fbae76a37829205e04279f220a26af2.0;i=a1.
Via: SIP/2.0/TLS 52.114.76.76:5061;branch=z9hG4bKd216a55.
Record-Route: <sip:FQND_IP;lr;r2=on>.
Record-Route: <sip:FQND_IP:5061;transport=tls;r2=on;lr>.
Record-Route: <sip:sip-du-a-eu.pstnhub.microsoft.com:5061;transport=tls;lr>.
Contact: <sip:1005@CLIENT_IP:55766;transport=UDP;rinstance=d47edf336726e940>.
To: <sip:+34560@FQND:5061;user=phone>;tag=de4e6b45.
From: "Javier Gonz..lez Mu..oz"<sip:+324@sip.pstnhub.microsoft.com:5061;user=phone>;tag=c17bb1eb7f8649d4a89d8d4a876ac32b.
Call-ID: c1364913e582553a9a9c2544c3583b0a.
CSeq: 1 INVITE.
User-Agent: 3CXPhone 6.0.26523.0.
Content-Length: 0.

U CLIENT_IP:55766 -> FQND_IP:5060 #3
SIP/2.0 200 OK.
Via: SIP/2.0/UDP FQND_IP;branch=z9hG4bK7bb5.0fbae76a37829205e04279f220a26af2.0;i=a1.
Via: SIP/2.0/TLS 52.114.76.76:5061;branch=z9hG4bKd216a55.
Record-Route: <sip:FQND_IP;lr;r2=on>.
Record-Route: <sip:FQND_IP:5061;transport=tls;r2=on;lr>.
Record-Route: <sip:sip-du-a-eu.pstnhub.microsoft.com:5061;transport=tls;lr>.
Contact: <sip:1005@CLIENT_IP:55766;transport=UDP;rinstance=d47edf336726e940>.
To: <sip:+34560@FQND:5061;user=phone>;tag=de4e6b45.
From: "Javier Gonz..lez Mu..oz"<sip:+324@sip.pstnhub.microsoft.com:5061;user=phone>;tag=c17bb1eb7f8649d4a89d8d4a876ac32b.
Call-ID: c1364913e582553a9a9c2544c3583b0a.
CSeq: 1 INVITE.
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE.
Content-Type: application/sdp.
Supported: replaces.
User-Agent: 3CXPhone 6.0.26523.0.
Content-Length: 1067.
.
v=0.
o=3cxVCE 324945090 117647850 IN IP4 .
s=3cxVCE Audio Call.
t=0 0.
m=audio 0 RTP/SAVP 104 9 103 111 18 0 8 97 101 13 118.
c=IN IP4 52.113.44.8.
a=rtpmap:104 SILK/16000.
a=rtpmap:9 G722/8000.
a=rtpmap:103 SILK/8000.
a=rtpmap:111 SIREN/16000.
a=fmtp:111 bitrate=16000.
a=rtpmap:18 G729/8000.
a=fmtp:18 annexb=no.
a=rtpmap:0 PCMU/8000.
a=rtpmap:8 PCMA/8000.
a=rtpmap:97 RED/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-16.
a=rtpmap:13 CN/8000.
a=rtpmap:118 CN/16000.
a=rtcp:50453.
a=ice-ufrag:FZTb.
a=ice-pwd:yD3P7nr+xNq0VYdv7xpB1F+Y.
a=rtcp-mux.
a=candidate:1 1 UDP 213

I never received ACK..

In my configuration:

Kamailio.cfg:

#!KAMAILIO
#!define WITH_TLS

event_route[tm:local-request] {

if(is_method("OPTIONS") && $ru =~ "pstnhub.microsoft.com") {
append_hf("Contact: <sip:FQND:5061;transport=tls>\r\n");
}
xlog("L_INFO", "Sent out tm request: $mb\n");
}

request_route{

remove_hf("Route");
if (is_method("INVITE|SUBSCRIBE")) {
xlog("L_INFO","$fU is trying to call to $rU con valores $tu\n");
$rU="1005";
}

}

What I'm doing wrong?

I don't understand why not received ACK..

Could anyone help me?

Thanks