GSM works based on AT command
1st u download the at commands and use it..
most of GSM works based on UART communication…..
so u connect ur gsm to ur controller thriugh rs232 and MAX232…….
when u get sms to ur GSm it gives the command as AT++CMTI: “SM”,1
thriugh this command u can decode ur message…
and one more imp thing is if ur sim message is full it will not show ur message……
first u delt ur sim message and try this……………………………
hope u undrstnd