Grandstream GXW-4104 - doesn't path through the early media

[e23cx]

Hello All,

I have an issue on outbound calls to a special service providers, where the audio is transferred before the call is established.
Besides of that issue I also can't hear original ring tone from the analogue line when I do any outbound calls. It looks like early media is not passing through.
Does somebody know how to enable it in 3CX on SIP trunk config for GXW-4104 ?

Thank you in advance!

 

[leejor]

You may have to see exactly what SIP messages are being returned from the gateway after DTMF has been sent. In many cases, that (right after DTMF spill) is when the call has been considered answered, and audio is cut through. You may have an option set that is awaiting something like a current reversal, or a timer involved, that needs to be "adjusted". I'm not familiar enough with that gateway to advise.

 

[e23cx]

I don't see any SIP messages returned from Grandstream (except Trying) after DTMF has been sent.

 

[e23cx]

I found the solution:
it was the incorrect FXO Termination line config on Grandstream. I don't know how it's related, but after I set " Polarity Reversal " & " Call Supervision " to NO, I started hearing early media and ringing tone.

Thank you for pointing me in right direction!

 

[leejor]

Probably, because the Gateway was set to expect "something", it was waiting, before cutting through the audio. When you tell it NO, which appears to be the default (so that must have been changed at some point), it cuts through right away.