Yes, as said, I am using SIM900 Module and its quite working with Arduino's library’s (Arduino 1.0.5 IDE).
Actually, my project is to manage messages, When a SMS is received, depending upon text in the message. Reply ll be sent. Kind of interactive service.
So, just used SMS class and it’s around 15K only.
Thank you for response, btw got my solution. I used Lot of strings in my code for giving apt reply.
The thing is whenever an array or string is declared, Memory is always allocated in SRAM. RAM over looded 
That is the reason for resetting my Arduino automatically all the time. Solution is to store them in FLASH memory using PROGMEM library
Thought if I share it will be Helpful 
