title: Send APDU commands to USIM/SIM card in android
body: <p>I was already worked with smart cards and I am familiar with APDU commands (that are defined in <em>ISO/IEC 7816</em> and <em>Global Platform</em> specifications). </p>
  
  <p>Now I want to know if there is any way to send an APDU command to my USIM/SIM card that is inserted to my mobile phone? (Samsung A3 with Android v4.4.4 kitkat installed.)</p>
  
  <p>I already searched in the Google and I found some related topics and tools named <em>SIM Toolkit Application</em> and <em>Seek for Android</em>. But I don't really understand what are these? Are these items two applications that I must install on my mobile phone? or are those two tools that was installed on the USIM/SIM card already and receive commands from the mobile phone?</p>
  
  <p>What is the difference between <em>Proactive commands</em> , <em>APDU commands</em> and <em>AT commands</em>?</p>
  
  <p>Should I learn android to develop SIM card applications or I just need Java Card specifications and ETSI standards?</p>
  
  <p>Thanks in advance.</p>