GSM 1.05 Library on Arduino Mega ADK doesn't work

Projects Networking, Protocols, and Devices
3

When you receive +CREG: 0,0 , it means that your modem isn't registered and is not currently searching a new operator to register to.
In other words, you can't do anything...

#include <SoftwareSerial.h>
SoftwareSerial gsm(10, 3); 
void setup()
{
  Serial.begin(19200);
  gsm.begin(19200);
}

void loop()
{
  if (gsm.available()) Serial.write(gsm.read());
  if (Serial.available()) gsm.write(Serial.read());
}

On serial monitor, send AT commands to the modem (Quectel_M10_AT_Commands_Manual_V4.0.pdf
AT -> must return OK
AT&F -> to reset to factory default ->must return OK
AT+CGATT?
// if +CGATT: 0 send AT+CGATT=1

let me know.