atcomsystems.ca/forum Forums TDM Business Telephone Systems Samsung Telephones & Systems Loss of audio when changing to private with public

If you are using the Public IP address of the system in the IP phones then make sure that it matches the entry of the Public address in the system Public address 1 slot. This would allow the phone to connect but no audio, if the IP's don't match up. Since you have tested the system behind a new out of the box router and things work without a hitch, then yes it is lead to believe that the existing firewall is causing the issue. Have them look at the port fowardings again. The main ones for IP phones are 6100, 6000, 9000 and 9001 all pointed at the processor. I do both UDP and TCP just to make sure. This may be a pain in the behind for some network people to do, but it's better than all them MGI ports.

The reason it is showing this, is because for IP phones port 9000 is the Audio port that it connects to. Forward that port just like the 6000 and you should have audio.

Your issue is that you haven't forwarded enough MPS (40000) ports.

You said you forwarded 40000-40015

Your wireshark trace shows the phone sending RTP packets to 40018 which you don't have forwarded.

Each MPS channel uses 4 ports, Each MGI channel uses 2 ports.

You need double the amount of ports forwarded with MPS then you do with MGI.

Port 6100 is used for SPNET and is TCP.
Port 6000 is used by the IP handsets to register to the system

Ports 9000 and 9001 are used by the phone to receive RTP and RTCP packets respectively, They don't need to be forwarded.

As you are calling from IP to IP it will use the MPS ports.
IP to TDM will use MGI.

I have a document from samsung here about the MPS function I can send if you want.

Nameless can you PM that documentation about MPS. Also I have a question to ask you in private about this subject. I want to clarify something before speaking of it in here.

pm sent

Thanks guys,

Sorry about the delayed response, things have been crazy busy. I really appreciate your help.

I've asked the IT guys to adjust the forwarding.

Another strange one though. The remote phones that have no audio are showing the Gateway address of the main site in the IP address field of 6.2.2 rather than the public IP of the remote site.

Would this be caused by VLAN configuration?

Thanks again!

It's a routing issue. The traffic is going over the vpn then out the main site internet connection, then back in again.
Some routers/firewalls have problems with loopback traffic.

If the traffic is going over a VPN then just connect to the internal IP address of the phone system using the phones. This should then allow for all audio to be passed if the VPN tunnel isn't blocking any ports.

Correct, assuming the phones are programmed to use the local address of the system

Correct Nameless. I would suggest it this way better since all the traffic from the other site is going through the VPN anyways. That way it doesn't create a loop.