Ring tone don't works correctly

Good morning,

I open this case other time because we continue with the same problems without solution.

In my company we are having some problems with the Ringing on incoming calls as the client call us and he doesn’t listen the ringing sound.

This only ocurred if I use SIP protocol, if I use IAX works correctly. Capturing traffic during the calls I see that we don’t send Ringing packets.
Also in the dialplan, if I use Answer and Wait the Ringing doesn’t works, however if I use Playback with a silence works perfectly:

;exten => s,n,Answer
;exten => s,n,Wait(2)
exten => s,n,Playback(silence/1)
exten => s,n,Queue(100,rTt)
exten => s,n,Hangup



Expected behaviour. Answer will terminate any ringback, and, if issued soon enough may pre-empt the ringback.

Note Answer is not strictly necessary in the above example, although, with SIP, letting Playback answer may not allow enough time for the media streams to stabilise before the announcement starts. Many people, wrongly, seem to believe that dialplans must start with Answer.

There may also be a question that something has to trigger sending of Ringing, in which case, you need to explicitly invoke Ringing, then wait before doing anything that could cause an answer.