atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems Remote IP phone getting hit from internet

System is SV9100.
We've had a lot of trouble with a remote IP phone. Bad connections, dropped calls, etc. I did a Wireshark capture at the remote end, and had NEC support look at it. They showed me where there is a public address trying to register to the phone's internal IP. After a lot of this, the phone crashes and reboots. They talked about port forwarding in the remote router to fix this.

The network guy says it wouldn't be port forwarding that is needed, but something in the router to block all traffic, except from the 9100's public address. And the cheap customer owned wireless router doesn't have that function.

Have I missed something all along that I should have done more setup on the remote end? Is the phone capable of doing this (only accepting traffic from the 9100)? Why would a remote IP phone do that anyway? Its only purpose is to communicate with the 9100, not anybody else on the internet.

Thank you.
Jim

I have never seen that. I have all my IP phones behind routers.

SIP scanners on the internet are probably hitting the router which is happily passing traffic through because it knows the phone is using port (well, you're talking on it so here's some traffic for it!). What I've been doing is move the SIP self port for the phone to a different port. seems to solve the problem.

Won't the scanners just find the new port you change to?

In theory, but they're usually canned scripts that are just trying the default sip port 5060 looking for something easy to hack. Trying 65000ish ports takes time and network resources.

So, change it in the phone, and in the 9100 program. And I suppose will have to change the other IP phones?

Jim

Actually what you want to change is the "SIP Self Port" under Networking/advanced/self port settings. That affects what the phone is using for it's local sip connection, not what it's talking to on the 9100. You won't need to touch the 9100 for that. It's just like having multiple phones on a nat connection.

That makes sense. And sounds better than changing lots of phones. I'll give it a try.

Thanks.
Jim