recieving messages from gsm

i am working on a embedded project using GSM SIM300.i am using Atmel at89s52, GSM module ,temperature sensor LM35.

Working of project- Temp sensor will sense the temperature and sent a message to my cell phone only if the temperature is above 30^c,,and if i sent a SMS to the cell phone(for eg-OK),the relay connected to the microcontroller should turn ON.My code is as follows-

#include<reg51.h>
#include<stdio.h>
#define MYDATA P1;
sbit ALE=P2^4;
sbit OE=P2^5;
sbit SC=P2^6;
sbit EOC=P2^7;
sbit ADDR_A=P2^0;
sbit ADDR_B=P2^1;



sbit MOTOR=P2^2;
unsigned char rx[20],msg[6];
unsigned char sensor1,adc1,r;

void clear(void)
{
unsigned char r;
for(r=0;r<100;r++)
rx[r]=0x00;
}


void clear1(void)   //user msg
{
unsigned char n;
for(n=0;n<=5;n++)
msg[n]=0x00;
}

void serialcomm()
{

 TMOD=0x20;        // Mode=2
 TH1=0xfd;         // 9600 baud
 SCON=0x50;        // Serial mode=1 ,8-Bit data,1 Stop bit ,1 Start bit  , Receiving on
 TR1=1;           // Start timer

}
void delay(unsigned int value)
   {
     unsigned int i,j;
     for(i=0;i<value;i++)
     for(j=0;j<1275;j++);
   }

void serial(unsigned char x)
{
        SBUF=x;
        while(TI==0);
        TI=0;
}

void Send2Gsm(char *aaa)
{
     while(*aaa!='\0')
                 {
                         serial(*aaa);
                         aaa++;
     }
}



unsigned char convert(void)
{       unsigned char value;
        delay(1);
        ALE=1;
        delay(1);
        SC=1;
        delay(1);
        ALE=0;
        SC=0;
        while(EOC==1);
        while(EOC==0);
        OE=1;
        delay(1);
        value=MYDATA;
        OE=0;
        return(value);
}


void receive_data()  interrupt 4     // Function to recieve data serialy from RS232 into uc
 {
 unsigned char r;
  rx[r]=SBUF;                       // Read sbuf
  RI=0;

 }
void main()
{
        char string1[10};
        int temp;
  serialcomm();
  Send2Gsm("AT\r\n");
  delay(2);
  Send2Gsm("AT+CMGF=1\r\n");
  delay(2);
  Send2Gsm("AT+CMGS= +918762357075\r\n");
  delay(2);
  Send2Gsm("hello");
  serial(0x1a);

  while(1)
  {
  ADDR_B=0;
        ADDR_A=0;
        sensor1=convert();

        if(sensor1>60 )
        {
                temp=(adc1*0.489);
                sprintf(string1,"%d",temp);

                delay(500);
                Send2Gsm("Temperature=");
                Send2Gsm(string1);
                Send2Gsm("*c");
                delay(500);

                serial(0x1A);
                delay(500);
                IE=0x90;
                while(rx[r]=='?')
   {
     IE=0x00;   //disable interrupt


     if(rx[0]=='*' && rx[1]=='O' && rx[2]=='N' )
    {

     MOTOR=1;
     clear();
     clear1();

    }

   else if(rx[0]=='*' && rx[1]=='O' && rx[2]=='F')
    {

       MOTOR=0;
       clear();
       clear1();

    }
    }


}
}
}

i am not getting output with this code.i am having doubt with the recieving sms to the gsm modem.can anyone point out the mistakes in my code ??