REDMOND, Wash.— Microsoft Corp. employees are passionate users of the latest tech toys. But there is one gadget love that many at the company dare not name: the iPhone.

The iPhone is made, of course, by Microsoft's longtime rival, Apple Inc. The device's success is a nagging reminder for Microsoft executives of how the company's own efforts to compete in the mobile business have fallen short in recent years. What is especially painful is that many of Microsoft's own employees are nuts for the device.

The perils of being an iPhone user at Microsoft were on display last September. At an all- company meeting in a Seattle sports stadium, one hapless employee used his iPhone to snap photos of Microsoft Chief Executive Steve Ballmer. Mr. Ballmer snatched the iPhone out of the employee's hands, placed it on the ground and pretended to stomp on it in front of thousands of Microsoft workers, according to people present. Mr. Ballmer uses phones from different manufacturers that run on Microsoft's mobile phone software.

A Microsoft spokeswoman declined to comment and declined to make executives available for this story.

Apple CEO Steve Jobs referred an email asking about iPhone use at Microsoft to a spokeswoman, who declined to comment.