Minimum system requirements
To use iCloud, you need at least iOS 5 on iPhone 3GS
Calendar, Contacts, Mail
Calendar, Contacts, and Mail are available on iPhone, iPad, or iPod touch, Mac, and PC.
Minimum Requirements:
iOS 5
OS X Lion 10.7.5
Windows 10 May 29, 2019 Update or later with iCloud for Windows 10 or later and Outlook 2016 3
To view all minimum system requirements by feature, click here.