title: AT+CSQ? returns error
body: <p>I need help, i am working with Arduino UNO and a GPRS shield, which is powered with an adapter that outputs 12v 500mA. The sim card is placed properly, i checked this with the <strong>AT+CPIN?</strong> command, but when i try to check the signal level with <strong>AT+CSQ?</strong>, it just return <strong>error</strong>. Please can someone help me.</p>
  
  <p><a href="https://i.stack.imgur.com/OOeiX.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OOeiX.jpg" alt="ERROR IMAGE FORM SERIAL MONITOR"></a></p>