No audio on 3cx desktop apps.

[Timothy108564567864]

3cx Server Version: 18.0 Update 2 (Build 314)
3cx Desktop app Version: 18.7.10

Let me start with saying that all mobile and desk phones are working fine.

I have recently discovered that I do not have two way speech on my desktop apps as you can see by the Wireshark the call is completed, but when you listen to the call using Wireshark, only the ringtone and the external number was playing sound, But there is no sound both ways on 3cx.
Secondly when I connect to my telephone network using a VPN the voice traffic works fine. My NAT config is attached please note that I am mimicking a full cone Nat on my Mikrotik for the built in 3cx firewall check to pass.

 

[NickD_3CX]

Hi!

I'm not sure I understand exactly how you have set this up.

You say "when I connect to my telephone network using a VPN the voice traffic works fine", so from this I assume that the PC that is running the 3CX Desktop App is on a different LAN than what the 3CX Server is. Is this correct?
Can you explain the network exactly? Do you have VLANs and both Desktop App and 3CX Server are behind the same Public IP?

Also could you explain when you mean when you say "mimicking a full cone Nat"?

Last question, when you dial *777 from your 3CX Desktop app and speak into the mic, do you hear your voice back?

 

[Timothy108564567864]

Hi

We are running different network on different switches witch does not link to each other each switch is dedicated to its own network.
Vlan's: No
Desktop App: Connected externally from home with different service provider. (I can reproducer this problem with my desk top app from my house too as well as on a different network inside the office)
Public IP: The 3cx Server has a Dedicated static IP witch is not being used for anything but the Voice network.
Full Cone: A Mikrotik router does not have a full cone Nat fetcher thus I am forwarding all traffic through my NAT's to the 3cx Server.
Eco: When dialing *777 I get the same result. Witch is no voice

 

[NickD_3CX]

As a first step, I would suggest running the Firewall Checker again in 3CX, just to make sure it finds the ports 9000-10999 open.

If that is OK, then the next thing to check is the Audio Packets are being received by both ends.
You can use Wireshark to check this, but not the way you did in the screenshot:

1. On the PC where you have the Desktop App, start capturing with Wireshark
2. Call *777 and speak into the mic
3. Hang up the call and in wireshark filter with a filter something like
   

   ((udp.dstport>=9000 and udp.dstport<=10999) or (udp.srcport>=9000 and udp.srcport<=10999)) and ip.addr==<PUBLIC IP OF 3CX>

You should see packets from the 3CX Server to your PC from port 9000-10999 to a random port, and from the random port on your PC to the 3CX Server to port 9000-10999.

Then do the same, but this time, capture on the 3CX Server (Dashbord --> Activity Log --> Capture) and in the filter just put the Public IP of the location where the Desktop App is.
Again, you should see packets being delivered in both directions.

Use only *777 (echo test extension) to rule out any other problems. My guess is that in one of these cases, you will see packets only being delivered in one direction and that is where you will need to focus your attention to figure out what is happening.

From your description, by the time it works when you connect via VPN, I think it is not a 3CX software problem, rather a network config.
I hope this advice helps you narrow it down.