Shahzad,

In some cases manufacturers only provide datasheet and no application circuit e.g. you will not find any application circuit for AT89C51 in the datasheet.

Most of the time, analog IC datasheets contain application circuit diagram e.g. U3759B from ATMEL.

I can't understand what other information do you need?

You can control MUTE of speech circuit with 8051, also you can dial a number with 8051 using pulse dialing (even DTMF dialling can be performed using a micro)

All it depends upon you how do you want to control your speech circuit? What functions are required?

Please be little specific, I think you are still trying to interface 8051+ISD chip.

IA