title: iOS canOpenURL: how to return NO when no sim on iPhone?
body: <p>I use UIApplications' canOpenURL to check if the device can make phone call using "tel:" scheme, but it return YES when the app runs on iPhone <strong>WITHOUT</strong> sim, in this case, the phone cannot make call, but it still returns YES. Is there a way to check if the iPhone can really make call?</p>
  
  <p>Thanks!</p>