We have an internet customer with a panasonic phone system connecting to a Broadvox SIP trunk. After a power outage, their phones quit working. a day and a half of troubleshooting away, we had to default their Fortigate Firewall (we had removed all session helpers from the config previously) to get a test SIP client to connet to their broadvox trunk.
The phone system would still never establish behind the fortigate or an air router (the air router is what led us to realize the SIP session helper needed to be back) Here is the odd thing, the phone system will never register, until we bring up any SIP client on their network. We tested with a Fortivoice SIP handset using their account. we bring it up, the phone system comes up. We ended up putting a little sip client on a PC to connect uop if the phone system is restarted. we believe this is narrowed down to being a panasonic issue. I am not 100% clear on the details of how a sip trunk works. But here is what I suspect. The phone system had been up and registered for a long time, it was staying connected via that registration. In the mean time the provider has changed something in their communications or protocols that was designed to make their service more friendly by utilizing SIP helpers, etc. When they lost power it finally had to establish a new registration connection, and everything went to shit. The Panasonic is on old old old firmware, so it might be having a communication issue (hes scheduled saturday to update). Its just odd that the only way to get the phone system to register is to establish the same connection from a different device first on the same network segment. anybody ever come across something like this? I never could get a good packet capture on our edge router to see the associated packets well. the only visibility I ever got was at our POP where I saw the udp 5060 connection, but it had 0 bytes, like the headers were there for the packets, but there wasnt any actual payload. I really wish the firmware on their site firewall allowed a pcap export, I would like to see the communications taking place. -- All parts should go together without forcing. You must remember that the parts you are reassembling were disassembled by you. Therefore, if you can't get them together again, there must be a reason. By all means, do not use a hammer. -- IBM maintenance manual, 1925
