Ensure non-device-owned properties are not overwritten by the device.

Common/Models/DeviceModelConstants.cs

@@ -33,6 +33,11 @@
         public const string UPDATED_TIME = "UpdatedTime";
         public const string HOST_NAME = "HostName";
         public const string ICCID = "ICCID";
+
+        /// <summary>
+        /// The list of properties not owned by the device.
+        /// </summary>
+        public static readonly string[] External = { ICCID };
     }
 
     public static class CommandModelConstants

DeviceAdministration/Infrastructure/BusinessLogic/DeviceLogic.cs

@@ -235,10 +235,17 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.DeviceAdmin.Infr
             dynamic existingDevice = await GetDeviceAsync(DeviceSchemaHelper.GetDeviceID(device));
 
             // Save the command history and the original created date of the existing device
-            if (DeviceSchemaHelper.GetDeviceProperties(existingDevice) != null)
+            dynamic existingDeviceProperties = DeviceSchemaHelper.GetDeviceProperties(existingDevice);
+            if (existingDeviceProperties != null)
             {
                 dynamic deviceProperties = DeviceSchemaHelper.GetDeviceProperties(device);
                 deviceProperties.CreatedTime = DeviceSchemaHelper.GetCreatedTime(existingDevice);
+
+                // Save existing external properties to the updated device
+                foreach (string ext in DevicePropertiesConstants.External)
+                {
+                    D.Dynamic.InvokeSet(deviceProperties, ext, D.Dynamic.InvokeGet(existingDeviceProperties, ext));
+                }
             }
 
             device.CommandHistory = existingDevice.CommandHistory;