3CX disconnects calls over Fortigate VPN ** SOLVED

[gshalev]

Hi,
I have recently installed the 3CX PBX in the office. I am really pleased with it except that I can't get it to work over a VPN.

I connected it to my "legacy" PBX using the following SIP gateway - Audiocodes MP-114 (config taken from this web site).
1. When I place calls inside the office using the 3CX phone, I am able to place and receive calls through the SIP gateway.
2. When I connect to the 3CX from home using the 3CX phone I am able to place calls to the SIP extensions (able to leave voice messages), but when I try to establish a call through the gateway the call is dropped the second the other party answers the call.
3. I tried using tunnel mode through the VPN with no luck. Same behavior as above.
4. Tunnel mode worked when I opened a port on my firewall (Fortigate WIFI 80CM, firmware v4.0,build0185,091020) , however I don't like this idea too much, due to the fact that the 3CX isn't on the DMZ.

I also bought a SNOM 370 phone and the behaviour is exactly the same, calls to the outside via the SIP gateway are being dropped when connecting through the VPN, however inside the office everything is working fine.

I would really appreciate your help on this.

Thanks & Happy new year!!!
Guy

 

[semn]

Re: 3CX disconnects calls over Fortigate VPN

Can you tell us what version of the firmware you use in MP box?
If you experience the same type of issue when you try to call from outside using the SNOM phone my suggestion is to take a look at the firewall settings.
Happy New Year

 

[gshalev]

Re: 3CX disconnects calls over Fortigate VPN

Hi,
Thanks for the reply.
The firmware version is:
5.80a.023.006

Thanks,
Guy

 

[semn]

Re: 3CX disconnects calls over Fortigate VPN

The firmware version it's ok. Can you tell us if you use STUN ? Did you perform a a firewall test to see if the date flow correctly over the firewall. Like any security gateway ( i have experience with Cisco boxes like ASA55xx) the default firewall settings are very restrictive.
From what i see your issue is generate by the firewall not by the MP-114.
Have a nice day.

George

 

[gshalev]

Re: 3CX disconnects calls over Fortigate VPN

Hi,
Thanks a lot for your inputs.
I root caused the problem, apparently I didn't configure the default gateway for the MP-114 box.
During installation I was under the assumption that SIP calls are routed through the 3XC systems and thus there is no need for the gateway. As it turns out I was wrong
SIP calls are a direct connection between MP-114 to the caller.

Thanks again for your time,
Guy