How can I send and recieve packets of data using TAPI

Sir,
I am developing a communication application using TAPI
and VC++.In my application I connect two remote machine
using PSTN.Both machine send and recieve data simultaneously.
Basicly ,I want to send voice with data. So I have planned that ,I
will created separate voice and data packet and first send number of
voice packet required to send a telephone quality sound.Than I
will utilise remaining bandwidth by sending data packet.So I want to
send and recieve mixture of voice and data packet.Someone have adviced
me to refer TapiComm application.But that application used ReadFile
and WriteFile function with overlapped structure.Using this technique
I can only send and recieve a file not a separate packets.Can I use any
WSASend or WSARecv in overlapped I/O mode like mecanism to send
and recieve data using TAPI. If ReadFile and WriteFile is only option than
how can I achieve my task using these function.Please guide me.