title: +CMS ERROR: 304, sending message using at command
body: <p>Im new to GSM and AT command sets,</p>
  
  <p>based on the error +CMS ERROR: 304 its a <strong>Invalid PDU mode parameter</strong> according to <a href="http://www.activexperts.com/activsms/sms/gsmerrorcodes/" rel="noreferrer">activexperts</a></p>
  
  <p>Im trying to send message using AT command to GSM modem in PDU mode</p>
  
  <pre><code>AT+CMGF=0
  OK
  
  AT+CMGS=31
  &gt; 079136190700203911000C913639350768260000AA13C834A89D07B9C3ED32283D0751C3F3F41B
  
  +CMS ERROR: 304        
  </code></pre>
  
  <p>Can you help me guys what did I missed or mistake?  <a href="http://www.smartposition.nl/resources/sms_pdu.html" rel="noreferrer">I used this to encode the PDU</a></p>
  
  <p>Thanks guys.</p>