title: In-App Billing isBillingSupported - returns what and functions how?
body: <p>The question is based around the Google In-App Billing service for Android. Specifically the function <code>isBillingSupported</code>.</p>
  
  <pre><code>int result = mBillingService.isBillingSupported(3, mOwner.getPackageName(), "inapp")
  </code></pre>
  
  <p>Firstly, what does this function return? The docs are incredibly secretive on this:</p>
  
  <blockquote>
    <p>RESULT_OK(0) on success, corresponding result code on failures</p>
  </blockquote>
  
  <p>The <a href="http://developer.android.com/google/play/billing/billing_reference.html" rel="nofollow">only codes I found</a> seem unrelated to the question of billing being supported. All that seems concrete, is that 0 is successful. What errors can there be?</p>
  
  <p>Secondly, what does this function check for to know whether billing is supported? I have a phone that is completely capable of In-App billing, and this function does indeed return "true" when I am connected to a reasonable internet source, such as WiFi. However, if my connection is less stable, it will not return "true". So I assume that it checks for a good connection. What else does it check for?</p>