title: Throttles, Quotas and Pricing of Azure IoT Hub
body: <p>After reading about the throttles and quotas of Azure IoT Hub, I am struggling to understand how an IoT Hub can support millions of devices (Microsoft's promise). Maybe you guys can help. These are my thoughts so far:</p>
  
  <p>Quote from <a href="https://azure.microsoft.com/en-us/documentation/articles/iot-hub-devguide/#throttling" rel="nofollow">Microsoft doc</a></p>
  
  <p><strong>Device connections:</strong></p>
  
  <blockquote>
    <p>120/sec/unit (for S2), 12/sec/unit (for S1).  Minimum of 100/sec. For
    example, two S1 units is 2*12 = 24/sec, but you will have at least
    100/sec across your units. With nine S1 units you have 108/sec (9*12)
    across your units.</p>
  </blockquote>
  
  <p><strong>12/sec/unit</strong> - does it mean that if I only have one scaling unit I can have max. 12 simultaneous connections at the same time? 
  Or does it mean that I can open max. 12 new connection per second?</p>
  
  <p><strong>What does "Minimum of 100/sec" mean?</strong></p>
  
  <p>IoT Hub supports AMQP 1.0.
  My understanding was that with this protocol I can have a permanently open device &lt;--> cloud connection to be able to send/receive messages "in real time". It would not be possible to support more than 12 devices with a single scaling unit if only 12 simultaneous connections were allowed.</p>