Yealink Phone to Phone no sound

[Annette]

I have 5 lines all the same phones Yealink T21P E2, when any of the phones call another desk phone there is no sound. When we are transferring a call from outside to another line, we can not hear each other but when the call is transferred we can hear the outside caller. I am also able to call from my mobile 3cx soft phone to another extension and we can both hear each other. From soft phone to desk phone works. Desk phone to desk phone does not. The phone says they call is connected, we have no errors just no sound.
Thank you for any help.

 

[eddv123]

Just from reading this I would surmise you are probably using multiple STUN phones from a hosted 3CX system?

However please advise as to your network and system setup.

 

[Annette]

I have 5 lines all hosted by 3cx, Flowroute.

 

[eddv123]

What method are the phones setup in? VPN, SBC or STUN ?

 

[Annette]

VPN google hosted.

 

[eddv123]

Normally not required in VPN setup however have you looked at enabling PBX delivers audio on the extensions to see if that solves it.

I would check your firewall for the correct port forwarding also, audio ports 9000 - 10999 required.

 

[eddv123]

Failing that run a Wireshark capture (with Yealink you can run one in the actual interface of the phone) you maybe able to then see where the audio traffic is stopping.

 

[DavidA]

Have you checked the FlowRoute "Direct Audio" firewall requirements? Inbound ports need to be allowed from any host as i recall. We had a similar issue a while back with FlowRoute.