Recently moved a 7100 behind a firewall for a customer. They have 2 remote ipt phones connected to the system, 2 different locations. Problem is the 2 remote phones can't call each other. They can call and receive calls from anyone inside the office where the OS 7100 is located, but not each other. They were working fine before the firewall.

Any ideas?

check the ports in the firewall. I don't have the list handy at the moment but you should be able to find it on the GSBN website.

We did check port forwarding. Had to forward 6000, 9000, 30000-30011 before the phones would work which we knew. Not sure if there is another port required for the 2 phones outside the office to be able to call each other.

the ones I can remember are 6000 tcp/udp, 6100 tcp, 30000~30031 RTP/UDP, 6000 UDP, 9000 and 9001 RTP RTCP

IP to IP uses MPS channels and those use ports 40000-40031

You could forward those ports too or disable MPS under SystemOptions MPS = No

Thanks for the suggestions guys, we will open up some more ports and see if that works. I'll report back what changes made a difference.

Since the remote phones should talk peer-to-peer it sounds like you don't have a valid route between remote sites. Can you ping one remote ip address from the other remote site?

I thought the ip phones had to be on the same private subnet to talk with no mgi channels. Is this not the case?

IP to IP will use MPS by default. Forward ports 40000-40031 in your firewall to your Samsung or turn off MPS service.

Also, under LAN settings, make sure you're set for Private with Public and both your internal and static WAN IP addresses are listed.

You can remove the 9000, 9001 ports as they used to be required at the ip phone end (in the early days of the OS100/OS500, before the public with firewall option was added into the IP Phone settings MMC)