The main theme of project is, send/receive SMS via PSTN, using FSK Protocol in the attached devices. For that, I select 89S51 microcontroller and XR-2211/XR2206 for FSK transmitter/receiver.
The problem is that I have no proper schematic for the selected components. How I can assemble em?
Why use FSK??? I think you can directly use DTMF signals generated by telephones to transmit the data from source to receiver. FSK might rather complicated the project.
If you still decide to go ahead with FSK, first try to go thru the data sheet for XR-2211 and XR-2206. That should give you some idea of how to implement it.