Also, found in log:

Jan 13 12:49:32 orl-ar-openser01 /usr/sbin/kamailio[1313]: NOTICE: <script>: request_route() -> 72.31.12.137:5060 sent INVITE From: sip:2053140346;isub=33343@72.31.12.137 To: sip:16077751765@71.44.15.84:5060;user=phone with PAI: sip:2053140340@67.9.220.145 CID: SDr1ra601-881f71e7d022d9c4ae64dfccd6ff916c-8q7og02

Jan 13 12:49:32 orl-ar-openser01 /usr/sbin/kamailio[1316]: NOTICE: <script>: onreply_route() -> 65.32.14.217:5060 sent reply: 100 reason: Trying From: sip:2053140346@72.31.12.137 To: <null> for CID: SDr1ra601-881f71e7d022d9c4ae64dfccd6ff916c-8q7og02


From: sr-users <sr-users-bounces@lists.kamailio.org> on behalf of AL S <alirsm2@outlook.com>
Sent: Thursday, January 14, 2021 8:57 AM
To: Kamailio (SER) - Users Mailing List <sr-users@lists.kamailio.org>
Subject: [SR-Users] To header being malformatted.
 
Hi,

We noticed an issue with the way the Kamailio is handling certain messages being sent to them, specifically, the To header being relayed from Kamailio to the next hop is malformatted. 

Any assistance is greatly appreciated

INVITE received by Kamailio:

  Request: Invite
                        Request URI: sip:2053140346;isub=33343@72.31.12.137:5060;transport=udp
                               From: <sip:+13037819601@71.44.15.84;user=phone>;tag=gK00a85927
                                 To: <sip:+12053140346@72.31.12.137>;tag=SDnpoa601-1c711123926
                            Call-ID: SDnpoa601-f1bc387aa5a486c1dd943d1b53ae8e6a-8q7og02
                               CSeq: 860668 INVITE
                            Contact: <sip:+13037819601@107.14.122.29:5060>
                             SDP IP: 0.0.0.0
                           SDP Port: 43126

INVITE forwarded by Kamailio:

 Request: Invite
                        Request URI: sip:2053140346;isub=33343@72.31.12.137:5060;transport=udp
                               From: <sip:+13037819601@71.44.15.84;user=phone>;tag=gK00a85927
                                 To: <sip:+120531403Oh.lc".3/+0]1..31.12.137>;tag=SDnpoa601-1c711123926
                            Call-ID: SDnpoa601-f1bc387aa5a486c1dd943d1b53ae8e6a-8q7og02
                               CSeq: 860668 INVITE
                            Contact: <sip:+13037819601@107.14.122.29:5060>
                             SDP IP: 0.0.0.0
                           SDP Port: 43126



Another example in BYE:



BYE received by Kamailio:

To: "WIRELESS CALLER" <sip:+18131111111@71.44.13.84>;tag=gK0a788ca6


BYE forwarded by Kamailio:

To: "WIRELESS CALLER" <sip:+18131112222A.++.+,-94


Thanks.
AL