So in our infrastructure, we have a freepbx behind a Sangoma SBC VM and we’re connecting to a SIP provider through a firewall that’s NATing.
We’re having some issues where after a certain amount of time, the SBC sip trunk to the ITSP provider will simply drop.
When we check the logs, it seems like on our side, the SBC keeps sending registration requests with a random rport and the other side accepts it and send it back to that random rport.
Here’s the transaction that the ITSP is receiving:
2019-10-09T17:37:04.634709Z|sip-forwarder|bc64ff9b-71c8-4d54-a8d5-f59a5aef32e0|IS|723| RECEIVED message from UDP:My IP:43035 at UDP:ITSP IP:5060:
REGISTER sip:ITSP IP;transport=udp SIP/2.0
Via: SIP/2.0/UDP My IP;rport=43035;branch=z9hG4bKrgUZ62QgDB7QH
Contact: <sip:username@My IP:5060;transport=udp;gw=To_ITSP>
To: <sip:username@ITSP IP;transport=udp>
From: <sip:username@ITSP IP;transport=udp>;tag=DZKB9QFXH186H
CSeq: 10767494 REGISTER
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, UPDATE, INFO, REGISTER, REFER, NOTIFY, PUBLISH, SUBSCRIBE
Supported: pw-info-package, path, replaces
User-Agent: NetBorder Session Controller
My question is, how we can change that rport with header manipulation or if it’s at all possible or maybe the problem is completely unrelated to that and you guys have suggestions.