Sim800 not recieve sms continously

[daveed442]

hello..am trying to build a program for controlling sim800 module.Now I stuck at a problem.. what my need is the sim800 will receive incoming message from different numbers.it should check all the numbers and if there is a particular message from a a particular number then only an output sensor is active and replying back to that particular number about the sensor status..
I tried various programs with my limited knowledge..sometimes it is working..but most of the time it is not reading the incoming messages continusly..please help .sorry for my english

[daveed442]

this is my program

String sms,aa,bb,cc;
long int dd=+918606****35;
void setup()
{
Serial.begin(9600);
Serial.println("AT");
Serial.println("AT+CMGF=1\r");
delay(2000);
aa=("AT+CSMP=17,167,0,0\r");
Serial.println(aa); //if both are true sending msg
delay(2000);

}
void loop()
{
while (Serial.available()>0) //checking for serial inputs

{sms=Serial.readString();   
Serial.println(sms);
delay(2000);  

if(sms.indexOf("on")>=0 && (sms.indexOf("+9185")>=0)) //checking both sms content and senders number with the predefined content
{
bb=("AT+CMGS="+9185"\r");
Serial.println(bb) ;
delay(2000);
Serial.write("device is on");
delay(2000);
Serial.println((char)26);
delay(1000);
}

delay(1000);
sms="";

}

}