problem sending sms using sim900 gsm shield

i am working with sim900 gsm shield from icomsat " " and i am looking for a code to send sms with this shield, i used many codes from the internet but none of it worked, i dont know if the problem is with the shield or not.

Lets see an example code?

Which Arduino are you using?

How have you got the Rx/Tx jumpers set?

ok i used this code with an arduino uno

#define SIM900_POWER 9

#include <SoftwareSerial.h>
#include “sms.h”
boolean started=false;
void setup()
//Serial connection.
Serial.println(“GSM Shield testing.”);

// Power on SIM900 module
pinMode(SIM900_POWER, OUTPUT);
digitalWrite(SIM900_POWER, HIGH);
digitalWrite(SIM900_POWER, LOW);
// end

//Start configuration of shield with baudrate.
//For http uses is raccomanded to use 4800 or slower.
if (gsm.begin(2400)) {
started = true;
else Serial.println("\nstatus=IDLE");

if (sms.SendSMS("+21652803677", “SMS from Arduino”))
Serial.println("\nSMS sent OK");


void loop()


this message appears in the Serial Monitor
"Trying to force the baud-rate to 9600

ERROR: SIM900 doesn’t answer. Check power and serial pins in GSM.cpp


If that's the example provided with the IDE it's trying to use pins D2 & D3 to communicate with the shield. Have you got your jumpers set to those pins? Or have you modified the library to use the pins you have selected?

no i didn't try any thing my friend i even don't know how to do that, could you help me!!

Try the example in the link in my signature. It's not for the shield you have but I'm sure you can tell what you need to change on your board.

Put one jumper between Tx and 2, and another between Rx and 3. The change the line in the code to

SoftwareSerial GPRS(2, 3);

That should work.

I am using an arduino uno and the example in the link in your signature doesn't work too :confused:

Doesn't work?

yes it doesn't work :confused: what should i do now?? thanks anyway

Does the serial relay sketch work? If not swap the jumpers over.

ok could you give me a simple code that you have tryed before with the Icomsat 1.1!!

All the code on that page works with it. I have one.

you mean " is for sale | HugeDomains "??? have you any video showing that am getting crazy :smiley:

now it works my friend it was just to put a jumper between Tx and 2, and another between Rx and 3. and do some changes in the GSM.cpp
it is done, i appreciate what you have done for me :slight_smile: