cordless mic as rf module ?

I am trying to use the cordless mic cktry as rf module.
Fot that i remove the mic as well as coupling capacitor and inject pc com port txd signal via max232 through the attenuator which is variable i adj. it for min./ sufficent voltage.
and insert the receiver in to pc audio-injack for test .
After some adj-ment i get the same waveform as at txd pin.
AS the output of receier is very low .
For that what can i do.
It is just matter of waveshapeing ?
Any guidline for the same

RS232 requires DC coupling, radio signals are AC coupled, you need to introduce some type of NRZ encoding such as Manchester coding to overcome this.

You should also use licence free radio modules, you don't have your location filled in?, but it's almost certain to be an offence to do what you're trying to.