Open VPN issue...sorta fixed, but need an explanation

[dfadayomi]

Hello everyone,

I have an issue with Open VPN. It may be that I don't understand how it works / should work, so any explanation would be appreciated.

I have two firewalls in different locations connected by Openvpn and two phone systems (one behind each firewall).

The Site to site VPN establishes fine and I can ping hosts on either side, however, voice communications have no sound.

Both phone systems act as peers of each other using their private IP addresses. The peer connection status shows that they're connected.

The VPN interface on both firewalls allows Any IPv4 traffic.

When I check the firewall logs, I see the client VPN side trying to connect to the phone system's private IP through the server side WAN interface, and then the server side blocks the communication.

I got voice to work by allowing the client side to communicate with the server side on voip ports, but I thought I shouldn't have to since all communication (I think) should be over the VPN using private IPs, right?

Please tell me where my logic is flawed.

Any explanation would be greatly appreciated.

Thank you

Dan