Two months ago, Microsoft announced that the minimum support level for Windows Phone, iOS and Android will be changed. So action is required if you have operating systems as described below.
End of support for Android 4.3 and lower
As from December all enrolled devices will be forced to retire from Microsoft Intune. The Company Portal app will coming closer to December only support 4.4 and higher.
End of support for iOS 8 and lower
At this moment the Company Portal only supports iOS 9, so there will not be an update for the devices with iOS 8. Make sure to replace the iOS 8 based devices soon since support will be deprecated after a while.
Mainstream support ended for Windows Phone 8.1
On the 11th of July mainstream support for Windows Phone 8.1 in general has been ended. The Windows Phone 8.1 devices however will still be supported by Intune but Microsoft advises to upgrade the devices to Windows 10 Mobile.