Media sent over TCP to port 5090?

[GeorgeTs]

Hello,

I am trying to debug a one-way / no-way audio issue that sporadically appears in one of our customers.
The customer is using 3cx phone for Windows v.16.3.0264 with their 3cx server running the 18.0.237 version.
After they reprovision their clients, issues stop, until they re-appear again some time the next day(s).

My questions, while trying to debug this thing in Wireshark traces captured both on the PC running the 3cx client and on the 3cx cloud server.

- Does the client actually send RTP over TCP (destination port 5090)? I believe that this happens indeed when the option "Use 3CX Tunnel for remote connections (3CX App only)" is enabled
- RTP over UDP sent by 3cx clients do not seem to be decoded in Wireshark, thus appearing as plain UDP packets. While clicking on those packet, right click "Decode as" and then selecting "RTP", I get an "Unknown RTP version 1" packet type, which cannot be played using the RTP player of Wireshark. Any idea why this happens?

Thank you in advance,
George

 

[NickD_3CX]

Hi George!

The Tunnel port, default 5090, needs to be forwarded for both UDP and TCP to your 3CX Server.

- Does the client actually send RTP over TCP (destination port 5090)? I believe that this happens indeed when the option "Use 3CX Tunnel for remote connections (3CX App only)" is enabled

It prefers UDP for the Audio part of the transmission, but can fall back to TCP, but should not happen very often.

- RTP over UDP sent by 3cx clients do not seem to be decoded in Wireshark, thus appearing as plain UDP packets. While clicking on those packet, right click "Decode as" and then selecting "RTP", I get an "Unknown RTP version 1" packet type, which cannot be played using the RTP player of Wireshark. Any idea why this happens?

Absolutely normal. The Tunnel encapsulates traffic, so they are not what Wireshark expects, thus can't decode them.
There is no way to listen to the Audio of a Tunneled connection with Wireshark. It's a fair guess though that if you see UDP packets flowing in both directions, that traffic is Audio.

 

[GeorgeTs]

Thank you @VasilisV_3CX
It has happened to 4 clients within the same network already.
Sometimes restarting the client works, sometimes restart is not working and deleting and reprovisioning the account does the trick.
I understand the best to be done at this point is contact 3cx support, or does this behavior ring a bell and you have a suggestion?

 

[VasilisV_3CX]

Hi @GeorgeTs,

There is no way to listen to the Audio of a Tunneled connection with Wireshark. It's a fair guess though that if you see UDP packets flowing in both directions, that traffic is Audio.

As per what my colleague mentioned, I would suggest having a look at the traffic you've captured before to see that the packets are moving in both directions. If not, you have isolated where the problem is and then yes, I'd suggest contacting support to assist.