Microsoft on Friday brought its Office software suite to iPhones but kept it away from Android devices and the iPad in an apparent attempt to protect sales of its Windows tablets. The software company quietly launched the application in Apple's App Store for those who buy an Office 365 subscription at $100 a year. Some analysts expressed puzzlement over Microsoft's strategy. "In their eyes, not providing Office for iPad will motivate people to buy Windows tablets. ... That makes no sense," said Frank Gillett, a Forrester Research analyst.