problem gsm shield M10

Hello everyone ,
i'm wroking with arduino mega2560 and gsm shield m10 , i'm looking for a code to send an sms. so i used this code
#include <SerialGSM.h>
#include <SoftwareSerial.h>
SerialGSM cell(2,3);
void setup()
{
pinMode(7, INPUT);
delay(30000); // wait for the GSM module
cell.begin(9600);
}
void textSomeone()
{
cell.Verbose(true); // used for debugging
cell.Boot();
cell.FwdSMS2Serial();
cell.Rcpt("+xxxxxxxxxxx"); // replace xxxxxxxxxxx with the
// recipient's cell number
cell.Message("This is the contents of a text message");
cell.SendSMS();
}
void loop()
{
if (digitalRead(7) == HIGH)
{
textSomeone();
}
if (cell.ReceiveSMS())
{
Serial.println(cell.Message());
cell.DeleteAllSMS();
}
}

can someone help me

the problem is that the sms couldnt be sent. what should i do ?