one-way audio with some numbers only

[bytesolutions]

Good morning everyone.
For a few days now I've been having one-way audio problems on calls with some numbers. I'll explain.
If I make and receive calls from my 3CX to mobile numbers everything works fine, if instead I make and receive calls from my 3CX to some landline numbers (not all) 3CX receives the caller's audio, but the caller does not hear me.
The system using a generic SIP trunk template as I am using the operator's SIP trunk.
The firewall test is completely green.
Analyzing the dump.pcap file in which the problem occurs, listening to the audio stream with wireshark, I hear both interlocutors correctly, which means that the audio reaches 3CX correctly.
I checked the codecs in the SIP trunk configuration and they are correct.
Could I fix it by enabling the "deliver audio through the PBX" option?
Could any of you help me solve the problem?
A thousand thanks

 

[erling]

I would try that.

We use several different SIP trunk providers, and they all have the "PBX Delivers Audio" box checked.

 

[bytesolutions]

I would try that.

We use several different SIP trunk providers, and they all have the "PBX Delivers Audio" box checked.

Hi erling.
Thank you very much for your answer. I'll try and I'll give you feedback.
Thank you