No Audio on external calls incoming and outbound

[Janik6882]

Problem: External Calls will show up but there is no audio on either end (this happens for both inbound and outbound calls)

Setup:

• Raspberry Pi 4 with 3CX v18 on it (just upgraded minutes ago but no differnce to v16)
• Switch connecting me to the FritzBox
• FritzBox 6591 Cable which serves as Router and SIP Trunk (It connects one of the landlines to 3CX on the Raspberry-Pi)
• One Yealink T42G and multiple Software based Phones (One Windows 3CX client, One Android 3CX client and another iOS 3CX Client on an iPad)

The Situation:
This all worked without any problems until I had two external calls which lasted approx. 1 hour each and now no audio is transfered on external calls. Audio still works perfect on internal calls from Windows to Yealink or on every other possible internal call configuration.

My thoughts:
Because the problem is with external calls only I'd expect the problem to be somewhere between FritzBox and Raspberry-Pi but I can't figure out what I am doing wrong and because I believe I never changed a Setting which affected the audio (I believe but I am not totally sure).

I'd really appreciate help because I have this Problem since approx. May or June and I switched back to my mobile phone although I actually came to like my Setup.
Thanks in advance for reading and taking time to maybe deal with this Problem.

 

[ChrisC_3CX]

First off, please let us know if you're able to completely pass the firewall test in "Management Console >> Dashboard >> Firewall".

Also, what SIP Provider are you using, is it a 3CX Supported one?

 

[Janik6882]

First off, please let us know if you're able to completely pass the firewall test in "Management Console >> Dashboard >> Firewall".

Also, what SIP Provider are you using, is it a 3CX Supported one?

Firewall Check: Because I never intended to access the 3CX Dashboard/Console outside of my local Network I never forwarded any Ports at my Router. The Results will be attached. My Internet/Phone Provider is Vodafone and the Fritz!Box also is from Vodafone and the SIP is running over the Fritz!Box but everything (also the SIP-Trunk) is local so I believe technically I'd be my own SIP Provider.

 

[ChrisC_3CX]

My Internet/Phone Provider is Vodafone and the Fritz!Box also is from Vodafone and the SIP is running over the Fritz!Box but everything (also the SIP-Trunk) is local so I believe technically I'd be my own SIP Provider.

Do you mean that your SIP provider gave you a local box that sits in the same LAN the PBX is in? If I understood correctly, is it actually on the Fritz!Box?

If that is the case, what you could do is perform packet capture on the 3CX PBX and then place an outbound call, you should be able to determine whether 3CX is sending any audio out to the Fritz!Box and whether there is any audio coming in from it. This will at least help you narrow down where the issue might be.

I'd suggest taking a look at our training material on basic troubleshooting which should provide enough info to perform the above task(slide 10-12): https://www.3cx.com/3cxacademy/videos/advanced/basic-troubleshooting/

Note: You can check out the video or read the speaker's notes for additional information.