Receive SMS and turn on and off the devices

void main () { clear(); lcdinit(); lcdcmd(0x80); lcddata('K'); delay(10); init(); SMSString("AT\r"); // AT commands to initialize gsm modem delay(50); SMSString( "ATe0\r"); // turn off echo delay(50); SMSString( "AT&W\r"); // save settings delay(50); SMSString( "AT+CMGF=1\r"); // select text mode for sms delay(50); SMSString( "AT+CNMI=2,1,0,0,0\r"); // notification of new sms delay(10); //New msg indication. // +CMTI: "SM",3 while(1) { clear(); IE=0X90;   // Enable serial interrupt delay(10); read_notification(msg1); IE=0x00; } }

void read_notification(unsigned char *msg) { unsigned char array[15],i,index_no; i=0; do {        msg++;         i++; }while(*msg!='+' && i!=15); // to check for first '+'. i=0; do {      array[i]=*msg++;      i++; }while(*msg!='\n' && i!=15);      // Check for new line. if(strncmp(array, "+CMTI", 5) == 0) {         array[14] = '\0';         IE=0x00;         lcdcmd(0x80); lcdstr("NEW MSG");// Just for indication.         delay(50);         SMSString("AT+CMGR=");         tx0(array[12]);         SMSString("\r");         IE=0x90;         delay(80);         read_text(msg1,rec_no,time_date);         delay(100); } return; }

How to send SMS using AT89c51

#include <REGX51.H>
#include <AT89X51.H>

unsigned char *command_AT = "AT\r";
unsigned char *command_CMGF = "AT+CMGF=1\r";
unsigned char *command_CMGS = "AT+CMGS=\"+910123456789\"\r";
unsigned char *message = "Hello Dear";
unsigned char CTRLZ = 0x1A;

void puts(unsigned char* ptr);
void putc(unsigned char chr);
void sendsms(void);
void initialize();

main()
{
initialize();
sendsms();
while(1);
}

void initialize()
{
SCON = 0x50; /*SCON: mode 1, 8-bit UART, enable receive */
TMOD |= 0x20; /*TMOD: timer 1, mode 2, 8-bit */
TH1 = 0xFD; /*TH1: for 9600 baud */
TR1 = 1; /*TR1: timer 1 run */
}

void sendsms()
{
puts(command_AT);
puts(command_CMGF);
puts(command_CMGS);
puts(message);
putc(CTRLZ);
}

void puts(char* p)
{
char *temp = p; /*temp pointer so that the actual pointer is not displaced */
while(*temp != 0x00)
{
putc(*temp);
temp++;
}
}

void putc(unsigned char chr)
{
SBUF = chr;
while(TI==0); /*Wait until the character is completely sent */
TI=0; /*Reset the flag */
}