title: Sending fullscreen, disappearing SMSs to an iPhone
body: <p>Where I live (Copenhagen, Denmark) there is a taxi company which offers to send you an SMS when the car you ordered is about to arrive.</p>
  
  <p>The SMSs are unlike any I have received on my iPhone in that they appear fullscreen and are not saved to the SMS application. See this screenshot:</p>
  
  <p><img src="https://i.stack.imgur.com/z2tCI.jpg" alt="A full screen SMS on an iPhone"></p>
  
  <p>As soon as you press "Dismiss" the message is completely gone. No trace of it in the SMS application.</p>
  
  <p>I was thinking that the ability to do this could be useful for apps in some way. Perhaps offered instead of a regular push notification for super important things. But most of all I am curious to learn what's going on.</p>
  
  <ul>
  <li><p>Is this a regular SMS or some sort of cell network alert?</p></li>
  <li><p>How can these be sent? Is it content formatting which triggers this special display or is it a protocol feature?</p></li>
  <li><p>How would they appear on other phones?</p></li>
  <li><p>If it is not a regular SMS but some sort of network alert would it be possible to send one to a 3G-enabled iPad?</p></li>
  </ul>