Rboy

Hi All I have wrote program in Visual Basic Its Using AT Command set to manage the modem and make Voice Calls But i had a proplem.The problem is I cannot transmit the voice.Ofc We re using Microphone, we can hear the voıce of the answerer but not able to transmit our voice, so my adviser asked me to use tapı to fix that problem if anybody know how to do it pls inform me. thnx a lot...