I'm able to send AT commands to GSM modem,
but i am not able interface my 8051 to GSM model.
can i get sample inerfacing code for 8051 micro controller.
"I am sending ATD command to GSM module. It gave me 'NO CARRIER'"
That means that it did not successfully connect to the called party.
Did you dial the correct number? Did the called party answer? Is that number data-enabled? (some operators require a separate number for data calls; some do not permit data calls on some tarrifs - particularly pre-pay)
"after this, when i tried it is giving 'NO DIAL TONE'"
Presumably, this means that you have no service - check the modem manual for more specific details.
Also check the modem manual to see if it can give any extended and/or more informative error information.
"my hardware is working fine because i am able to read hardware details of GSM module and also i can read SIM ID number"
That shows that you are communicating with the module; it does not show that you have GSM service, nor that the calls you are attempting are permitted for the SIM that you are using on the Network that you are using...