VPN to VPN 3CX calls not working

[sheras88]

Hey 3CXians,
I am new and need your help.
I have issues with the 3cx windows app when both sides are connected with the VPN.
for example.
3CX server is located on one network 192.168.88.8 (Public IP A)
Client 1 is on network 192.168.88.0 (Public IP A)(ext 1)
Client 2 is on network 192.168.0.0 (Public IP B)(OPENVPN)(ext 2)
Client 3 is on network 192.168.1.0 (Public IP C)(OPENVPN)(ext 3)

when Client 1 calls to the extension of Client 2 (ext 2) or Client 3 (ext 3) it works. and vice versa.
But,
when client 2 calls to the extension of Client 3 (ext 3), the app rings but there's no audio from both sides.

Could anyone of you guide me on how does will it work?
Thanks a lot,
Sheras

 

[rgruber]

Depending if you have a mesh VPN or site-to-site to Public A, you need an SBC so the phone calls can be controlled and routed properly. VPN can be unreliable when if comes to voice. A lot goes into the setup and planning. Are you using all phones or computer app, both?

https://www.3cx.com/docs/3cx-tunnel-session-border-controller/

 

[nobody]

Try what happens if you block the access to the tunnel port through the vpn. Clients then maybe will forced to use the Internet to connect to the pbx.

 

[JohnS_3CX]

Hi @sheras88

Generally VPN will only work if a remote client VPNs into the local network of your 3CX server, so that it appears its on the same LAN as the PBX.

That should work as simple basis, but given that VPNs can be set up a variety of ways and that some subnets may not communicate with others, it's not not guaranteed that your current setup will work. To help you, the PBX considers the following as local subnets based on RFC1918

10.0.0.0/8,169.254.0.0/16,172.16.0.0/12,192.168.0.0/16