GSM Shield says message send but doesn't receive

Hi, I’m using a gsm shield to send SMS messages, and I’m literally on the first step with the info at http://competefornothing.com/arduino-icomsat-v1-1-sim900-gsm-module-send-sms/

I used this code :

#include "SIM900.h"
#include <SoftwareSerial.h>
#include "sms.h"
SMSGSM sms;

int numdata;
boolean started=false;
char smsbuffer[160];
char n[20];

char sms_position;
char phone_number[20];
char sms_text[100];
int i;

void setup()
{
    Serial.begin(9600);
    
    if (gsm.begin(9600)) 
    {
        Serial.println("\nstatus=READY");
        started=true;
    } 
    else 
        Serial.println("\nstatus=IDLE");

    if(started) 
    {
        if (sms.SendSMS("+300000000000", "Arduino SMS"))
        {
          Serial.println("\nSMS sent OK.");
        }
        else
        {
          Serial.println("\nError sending SMS.");
        }      
    }
};

void loop()
{
    if(started) 
    {
        sms_position=sms.IsSMSPresent(SMS_UNREAD);
        if (sms_position) 
        {
            Serial.print("SMS postion:");
            Serial.println(sms_position,DEC);
            sms.GetSMS(sms_position, phone_number, sms_text, 100);
            Serial.println(phone_number);
            Serial.println(sms_text);
        }      
        delay(2000);
    }
};

When I first started … the code runs in the case of a transmitter and receiver, but now can not receive .

pls help me . :frowning:

Serial Monitor

status=READY

SMS sent OK.

status=READY

SMS sent OK.
SMS postion:-2


SMS postion:-2

pls help me . :frowning: