Help - randomly can't hear voice problem

[xchen]

when we call out, we don't hear the call ringing, and then the caller picks up, and we don't hear them speaking - but they claim they can hear us. If we hang up and try again, the call goes through and gets picked up, and everything is normal. It happens in reverse - someone rings us here, we pick up, can't hear a thing - then we or they hang up. They call again - and everything is fine. If it was once or twice, I wouldn't be too worried, but it's happened a bit in the past, and in the last couple of days, its happened on most calls in & out of the office. We've powered the phones down & up, but that's all I've tried, and doesn't seem to work.

we are using Yealink phones:
Firmware Version 7.60.0.110
Hardware Version 5.0.0.55

 

[Pierre_3CX]

Hi,
What model of yealink phone are you using please?

 

[xchen]

I think it is entry level one:
IP Phone SIP-T20P
Will double check next time in office (sorry, am from Australia and now 8pm on Friday).

 

[LukeyP]

Please try ticking the 'PBX delivers Audio' setting and if you have HP switches, please turn of LLDP.
I had both these issues in the past.

Cheers

 

[xchen]

I have just done the changes as suggested, and will report back with the outcome.

We don't have HP switch, it is a netgear switch, so guess would be no action needed.

Thanks mate!

 

[complex1]

we are using Yealink phones:
Firmware Version 7.60.0.110
Hardware Version 5.0.0.55
I think it is entry level one:
IP Phone SIP-T20P

The firmware version you are using is very old, I think.
Also it starts with “7” and this will say you are using the Yealink T22P phone, not the T20P.
May I suggest to update the firmware to the by 3CX supported version 7.71.0.224

 

[naked]

Hi,
I expect that you have done this, but make sure that the firewall check is OK. Port forwarding must be right, otherwise you do get one way audio.

Also it is true that you need to update your firmware. We find that the later Yealink firmware is a lot better.

 

[VoidRunner]

The one way audio usually is a problem related with the RTP protocol, and more precisely with the Network Package Delivery from host to host, which is a network issue.
Do you have any VPN Tunnels between the extensions and the server?
You may observe the 3CX logs (all of them). and watch for RTP word, saying unable to deliver audio to Host IP Address.
I've similar situation one or two years ago and fixed it by defining a static RTP port.

Greetings

 

[xchen]

Please try ticking the 'PBX delivers Audio' setting and if you have HP switches, please turn of LLDP.
I had both these issues in the past.

Cheers

Since I ticked the "PBS delivers Audio" for those extensions from 3CX server, those phones don't have this problem any more. Seems it does the trick! Thanks!

 

[xchen]

we are using Yealink phones:
Firmware Version 7.60.0.110
Hardware Version 5.0.0.55
I think it is entry level one:
IP Phone SIP-T20P

The firmware version you are using is very old, I think.
Also it starts with “7” and this will say you are using the Yealink T22P phone, not the T20P.
May I suggest to update the firmware to the by 3CX supported version 7.71.0.224

Thanks for bringing up the firmware version issue. I didn't think of this before. Will upgrade them to latest version!

 

[xchen]

The one way audio usually is a problem related with the RTP protocol, and more precisely with the Network Package Delivery from host to host, which is a network issue.
Do you have any VPN Tunnels between the extensions and the server?
You may observe the 3CX logs (all of them). and watch for RTP word, saying unable to deliver audio to Host IP Address.
I've similar situation one or two years ago and fixed it by defining a static RTP port.

Greetings

Awesome! Sounds complicated. Hopefully we don't have RTP problem, but will keep in mind. Thanks!