I can hear other side but they can't hear me

[InetGuy]

Hello,

I have a grandstream gxp2135 that I have provisioned and I can dial out just fine. I can hear the person on the other end just fine, but no matter what I try, they cannot hear me. I've tried a different phone, I've tried a different codec, neither work. I've also tried using the 3CX SIP app, and that works fine. However, when using the phone, no such luck.

Is there something i'm missing?

 

[Andyshawn]

You can try enabling "PBX delivers audio" in the Extensions Options menu for both extensions and see if that helps.

Also, disable SIP ALG in your router.

 

[eddv123]

This is normally going to be a firewall/network issue. So either port forwarding of audio ports has not been done or firewall rules (remote ends firewall blocking the inbound connection).

SIP ALG is always a good one to check also, depending on the firewall brand this can be a tick box in the GUI or sometimes a hidden CLI command.

 

[YiannisH_3CX]

Hello @InetGuy

You did not mention if the phone is provisioned as a local or a remote device. If remote are you using STUN or SBC?