help needed to interface micro with GSM modem

hi..i am new here....i am doing a project on home automation and security system....
in security system i am using a GSM modem for controlling the door lock system using a 4X3 (a general land phone's) keypad...
my concept is to interface the microcontroller to GSM modem and access the door opening through the micro...and in case,if the password entered is wrong, i need the micro to control the gsm modem...in such a way to send the SMS to pre-restored numbers...

can someone please provide me the programming code for this???
as i am beginner i request the program in an assembly language...


thanx for the help....

can you send the circuit diagram first. i can help you my friend
the details must be there. i mean which micro controller, what are the requirements etc