atcomsystems.ca/forum Forums TDM Business Telephone Systems Panasonic Telephones & Systems IP connection with two KX TDA100 – only half way works

IP connection with two KX TDA100 – only half way works

I’m setting up a ip connection inside a new company.
The company have two Offices.

Office A: public IP address
Office B: public IP address
Connection UDP port: 8000

Both offices have KX TDA100 PBX’s with their respective IP TRUNKS and IP EXTENSIONS cards.
They have two Panasonic IP phones.

When a call is made from a ip phone to any other phone inside the same LAN (using lan only) the call is established without flaw

When the call is made from an ip phone to any phone outside, at the other office (using internet) the call is established but half way, i.e. from the extension that’s inside the LAN one can speak but not to listen, and from the extension outside the LAN one can listen but not to speak (note: both sides transmit DTMF tones without trouble)

We’ve called the ISP to report this problem and says that his router is not blocking anything, but making a IP-map between ip public address and ip private address, this private address is 192.168.0.55 that corresponds to IP EXTENSION CARD ip address.

Any similar case?
Any hint will be appreciated!
Thanks.

You said you are connecting 2 kxtda 100's, and ip phones. are the 100's connected to each other ( Gateway cards )and then the ip phones are off the 100's on each side or are they on their own site connected through vpn to the 100's

True to be told, there’s no VPN established as such, but an ip address mapping done at the router, where routers public address is mapped directly to ip extensions card private ip address. (at the office A – only)

I understand the idea of verifying if the ports are not blocked, but the ISP guy says that everything is at default without blockings.

Although I think this network configuration is potentially dangerous, anyway I’d like to know why the call is established (I understand that a bidirectional link must exist for this to happen) but there’s no flow in one of the two ways.

Could it be that call establishing is done by TCP, and voice traffic over UDP?

I’ve been using a protocol analyzer to catch what’s happening inside the network, but I get no traffic from the 192.168.0.55 captured, neither UDP (voip) traffic from any point captured.

I’m moving to try a new tool it’s called PING PLOTTER to trace voip connections, any experience? Maybe I’m complicating a little, but in this case we want to work and learn on the fly.

There has to be a vpn for the external phone as the ip phones have to be mapped to the telephone system and be seen as on the internal network.

What ip has the external ip phone, it has to be on a different ip range to the system with a gateway through vpn routers to work and the system has to have the gateway setup through the vpn to the external site Plus you have to log on phone to ip card from remote site.