title: C2DM register frequency
body: <p>I'm testing the C2DM service. I implemented my code following this <a href="http://www.vogella.com/articles/AndroidCloudToDeviceMessaging/article.html" rel="nofollow">GUIDE</a> and made a little php script for sending the messages and everything runs correctly.</p>
  
  <p>Then I restarted the phone and (without opening the app) sent another message, and It was received too, so the how often have I to execute the <strong>com.google.android.c2dm.intent.REGISTER</strong> for always receive messages? Once per install or more frequently?</p>
  
  <p>Thanks!</p>