I have an Avaya 4602 IP phone which using H323 protocol, which is connected to Tomato 1.28 Shibby firmware. Router has an OpenVPN connection to VoIP server.
The phone appears to register fine with the VoIP server with H323 helper enabled (RTSP + SIP helpers disabled on the Tomato router) .
Problem I'm having is that callers can hear me, but I cannot hear them. Nor can I hear a dial tone when picking up the handset , but I can establish a call (albeit without audio).
I installed tcpdump on the Tomato router and monitored the Br0 interface , and noticed that RTP audio stream was being transmitted from the VoIP phone (192.168.1.199) to the VoIP server (192.168.0.4), however I couldn't see a RTP stream from the VoIP server back to the VoIP phone (i.e. 192.168.0.4 > 192.168.1.199)
I have had this behaviour before with our Linux routers (EdgeMax), and believe the issue was resolved by modifying INDIRECT-MEDIA and INDIRECT-SIGNALLING which is linked to the SIP Conntrack module.
I have tried various different combinations of switching off/on the helpers, none of the combinations appear to fix this issue.
My Linux knowledge is very limited, and wanted to know the following;
1. Does anyone know if this Tomato firmware has INDIRECT-MEDIA and INDIRECT-SIGNALLING parameters that can be enabled / disabled? if so how?
2. Is there a way to inspect/modify the conntrack module confignation? I have sniffed around using SSH and couldn't find config files.
3. Does anyone have any other ideas how to fix this?
I have spend several hours trying to troubleshoot without any success.
I have spent many hours trying to figure out why one way audio works with