is this possible that i play back a message stored in ISD Speech chip over telephone

Yes, it is possible.

what i want is that my 8051 diel a number and when it detects the call has been received on the other hand

You will need a DTMF dialer chip, and some call progress detection in order to properly detect that call has been answered.

please give me how the interface be developed with phone system in detail

Hard to answer :-)

I will look for some info later.

You must be aware of the legal requirements before you design and connect any equipment to the phone line

IA