Dear gurus

I am developing an application which dial a number and as soon the person lift the phone it play .wav sound file. Actually it is an advertisement application. We dial our customer number as soon the customer lift the phone our advertisement start playing. I have code to dial phone. But how we can know when he is lifted and as soon he lift the phone how to pass the wav file sound data through modem to phone. Can any one help me please.. If you have sample code I will be very thankful to you.

Thanks in advance for you great support

Gopi