Playback and record Simultaneously

Hi All,
The reason I want to do this is so that I can let the user recording their message know that they are approaching the end of a 30 second time limit. My idea is to have silence play back during the first 25 seconds of their recording and then playback a beep, followed by another 3 second later two more beeps before the message terminates. Any help would be greatly appreciated.

I suppose I could do this by dialing another extension, doing a monitor and then use the LIMIT_PLAYBACK_CALLER= true to prompt the warning, the problem here is that its part of a service loop, we want the user to be allowed to simply stop speaking and detect the silence to return to the head of our IVR…