Hello Daniel,

Look like transactions are not match when it send reply for NOTIFY. I think it should reuse connection.

Here SDP output where cseq are match and asterisk does retransmissions until time out.

Also I wonder where Path route is reused I see %* instead ; as delimiter between transport and port.

Retransmitting #8 (NAT) to 10.18.130.46:5060:
NOTIFY sip:191@192.168.88.246:5062;transport=tcp SIP/2.0
Via: SIP/2.0/UDP 10.18.130.51:5060;branch=z9hG4bK6939f20d;rport
Max-Forwards: 70
Route: <sip:inbound@10.18.130.46;lr;received=sip:client_public_ip:5062%3Btransport%3Dtcp>
From: "canlpbx02" <sip:canlpbx02@10.18.130.51>;tag=as4b212049
To: <sip:191@192.168.88.246:5062;transport=tcp>
Contact: <sip:canlpbx02@10.18.130.51:5060>
Call-ID: 14c7c8cc7335adf60f2be634132d3b2f@10.18.130.51:5060
CSeq: 102 NOTIFY
User-Agent: FPBX-12.0.43(12.8.1)
Event: message-summary
Content-Type: application/simple-message-summary
Content-Length: 89

Messages-Waiting: yes
Message-Account: sip:*97@10.18.130.51
Voice-Message: 24/0 (0/0)

---
Retransmitting #9 (NAT) to 10.18.130.46:5060:
NOTIFY sip:191@192.168.88.246:5062;transport=tcp SIP/2.0
Via: SIP/2.0/UDP 10.18.130.51:5060;branch=z9hG4bK6939f20d;rport
Max-Forwards: 70
Route: <sip:inbound@10.18.130.46;lr;received=sip:99.251.238.38:5062%3Btransport%3Dtcp> right here
From: "canlpbx02" <sip:canlpbx02@10.18.130.51>;tag=as4b212049
To: <sip:191@192.168.88.246:5062;transport=tcp>
Contact: <sip:canlpbx02@10.18.130.51:5060>
Call-ID: 14c7c8cc7335adf60f2be634132d3b2f@10.18.130.51:5060
CSeq: 102 NOTIFY
User-Agent: FPBX-12.0.43(12.8.1)
Event: message-summary
Content-Type: application/simple-message-summary
Content-Length: 89

Messages-Waiting: yes
Message-Account: sip:*97@10.18.130.51
Voice-Message: 24/0 (0/0)

---

<--- SIP read from UDP:10.18.130.46:5060 --->
SIP/2.0 408 Request Timeout
Via: SIP/2.0/UDP 10.18.130.51:5060;branch=z9hG4bK6939f20d;rport=5060;received=10.18.130.51
From: "canlpbx02" <sip:canlpbx02@10.18.130.51>;tag=as4b212049
To: <sip:191@192.168.88.246:5062;transport=tcp>;tag=dc299d9ac16f3377ac0b8dfa22eaf0a6-2fe2
Call-ID: 14c7c8cc7335adf60f2be634132d3b2f@10.18.130.51:5060
CSeq: 102 NOTIFY
Server: kamailio (4.2.3 (x86_64/linux))
Content-Length: 0

<------------->

Mar 23 08:45:47 canlvprx01 /usr/sbin/kamailio[20143]: ERROR: <core> [tcp_main.c:4338]: tcpconn_main_timeout(): connect client_pub_ip:5063 failed (timeout)