Device: NEC DSX 40 Hybrid Key Telephone System.
Local: Digital phones on site
Remote: IP Phone
Network Setup: Site-to-Site VPN
Firewall1: Checkpoint (Local)
Firewall2: Juniper (Remote)
We are attempting to get an IP phone to communicate with the telephone switch via VPN. We've setup the VPN between sites and are able to connect the phone to the switch. We can see the lights for lines in use. We can make and receive phone calls, BUT voice traffic is only one way (from IP phone out). The IP Phone cannot receive any audio.
My rationale is that through the VPN everything is open as far as routed traffic, so I'm at a loss as to why voice traffic is only going one way.
I have tried opening up ports to the device, but I don't believe that should make a difference and I'm trying to get internal voice going both ways, before I worry about external.
Any help will be much appreciated.