[How To] Get Device Unique Id in Windows Phone

To Get the device unique ID you need to first declare in the WMAppManifest.xml file this capability ID_CAP_IDENTITY_DEVICE.

You can use this ID to indentify one device (count unique users, send custom notifications, etc)

In code to get this Id you only need to do this:

public static byte[] GetDeviceUniqueID()
   {
      byte[] res = null;
      object uniqueId;
      if (DeviceExtendedProperties.TryGetValue("DeviceUniqueId", out uniqueId))
         {
            res = (byte[])uniqueId;  
         }
      return res;
   } 

Enjoy it!