Grandstream Phones One Way Audio

FreePBX Endpoints
1

New to FreePBX here.

I have two Grandstream phones which are showing as connected properly. I also have a MicroSIP endpoint on my desktop for testing purposes.

I am experiencing the following symptoms:

  • The MicroSIP can use echo test and audio plays
  • If the MicroSIP phone calls a Grandstream phone, the MicroSIP can hear the microphone from the Grandstream phone, but the Grandstream phone hears no audio
  • The Grandstream phone can dial echo test and it seems to connect, but there is no audio.

These are both on local networks, with the Grandstream on the same subnet as the FreePBX.

image

RTP Debugging shows that audio is being sent and received: No Audio Grandstream - FreePBX Pastebin

Any help would be greatly appreciated.

Thank you

2

In both the Grandstreams and the corresponding extensions, try disabling all codecs except ulaw (a.k.a. PCMU or G711u) and alaw (a.k.a. PCMA or G711a).

3

Thank you. That seems to have fixed it. I am surprised. I had enabled the other codecs in the SIP Settings, so I am not sure why they did not work.

Scott

4

Not your fault, Scott, G711 should always be the default selected by phones due to call quality issues with the compressing codes running over non-prioritized packet networks. G.729 and friends are relics from a time when carriers actually charged real money (and a lot of it) for antique circuits like 56k frame relay. They only work properly when voip traffic is prioritized and nowadays on gigabit ethernet networks hardly anyone ever does that. The Grandstream phones you have must be older models with even older firmware dating back to that time period.