Arduino Yun GPRS GSM Shield Seeedstudio v3.0

Hardware Arduino Yún
1

Hi all,

I am currently working on the GPRS GSM Shield Seeedstudio v3.0 (GPRS Shield V3.0 | Seeed Studio Wiki) and Arduino Yun.

I sent an sms and make voice call over the arduino yun.

However, I tested the following example to see if the modem of the GSM shield is working correctly.

#include <GSM.h>

// modem verification object
GSMModem modem;

// IMEI variable
String IMEI = "";

void setup() {
// initialize serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }

  // start modem test (reset and check response)
  Serial.print("Starting modem test...");
  if (modem.begin()) {
    Serial.println("modem.begin() succeeded");
  } else {
    Serial.println("ERROR, no modem answer.");
  }
}

void loop() {
   // get modem IMEI
   Serial.print("Checking IMEI...");
   IMEI = modem.getIMEI();

   // check IMEI response
   if (IMEI != NULL) {
     // show IMEI in serial monitor
     Serial.println("Modem's IMEI: " + IMEI);
     // reset modem to check booting:
     Serial.print("Resetting modem...");
     modem.begin();
     // get and check IMEI one more time
     if (modem.getIMEI() != NULL) {
       Serial.println("Modem is functoning properly");
     } else {
       Serial.println("Error: getIMEI() failed after modem.begin()");
   }
   } else {
      Serial.println("Error: Could not get IMEI");
   }
   // do nothing:
   while (true);
}

And then, I got the following respond as an output.

Starting modem test...ERROR, no modem answer.
Checking IMEI...Modem's IMEI: 0
Resetting modem...Modem is functoning properly

Also, I couldn't be able to make internet connection.

Does anyone have any idea about my problem?

Thank you for any help, it would be greatly appreciated.