Does calls from one extension to another extension on 3cx Desktop Apps works over Point-2-Site VPN?

[ictsys]

Hello All,
We have configured 3cx servers within our LAN environment. We have users working from home and some working in the office.
Scenario 1 - Calls made from an extension (with the laptop located in the office) to another extension (with the laptop located outside the LAN but connected to the office network via Point-2-Site VPN) works fine, both caller and callee are able to hear each other.
Scenario 2 - Calls made from an extension (with the laptop located in the office) to an external phone number works fine, both caller and callee are able to hear each other.
Scenario 3 - Calls made from an extension (with the laptop located outside the LAN but connected to the office network via Point-2-Site VPN) to an external phone number doesn't work, callee is able to hear the audio but caller is unable to hear the audio.
Scenario 4 - Calls made from an extension (with the laptop located outside the LAN but connected to the office network via Point-2-Site VPN) to another extension (with the laptop located outside the LAN but connected to the office network via Point-2-Site VPN) doesn't work, both caller and callee are not able to hear each other.

For Scenario 3 and 4, we noticed that the outbound traffic from the PABX to the caller shows the local IP of the LAN interface as its destination and not the Point-2-Site VPN tunnel IP obtained by the laptop.

Is it that 3cx does not work with Point-2-Site VPN?

 

[JohnS_3CX]

Hello,

Please ensure that the VPN is connected, before you launch the 3CX app.

Then retry your scenarios and see how it goes.

 

[ictsys]

Hello John,

Yes, I connected the VPN before launching the 3cx app but the issue persists.

 

[JohnS_3CX]

Please try the following as a test:

1. Edit 2 extensions to have the same following settings
2. Change the following setting to point to FQDN and then reprovision the extension, and ensure tunnel is also enabled

3. Verify the change will appear here in both fields



Run your test again once this is verified and tell me how it goes.

 

[ictsys]

Hello John,

Tried the above but it remains same. As mentioned earlier, the outbound traffic from the PABX has its Destination Address as the local IP address of my wireless interface card and not the IP address obtained by the Point-2-Site VPN tunnel adapter of my laptop.

 

[JohnS_3CX]

I think your VPN might not be compatible with the client for the following reason

- The client sees its local IP (the one your wireless card picks up)
- The VPN tries to catch the traffic and send it down the tunnel to the other end
- On the other end, the firewall will need to translate the IPs before sending them to the PBX
- It probably doesn't do the translation as expected, and the PBX sees the local IP of the laptop, hence it sends the traffic there
- The firewall is not aware of the fact that the laptop local IP is tied to the tunnel adapter on your laptop so it does not return the traffic there either (probably drops the packets)

What you should do is run a capture on the laptop and the PBX once the VPN has already been established, and then launch the app. I think it will confirm what we suspect to be the case.