It's thought that up to 10 per cent of Microsoft employees may be using Apple iPhones instead of handsets that run Microsoft's own software.
A report in The Wall Street Journal claims that last year ten thousand of the company's 100 thousand employees accessed the Microsoft employee email system using the rival firm’s device.
But while some employees are open about their iPhone habit, many others have taken to disguising their iPhone with generic cases or not answering it at all when bosses are present.
It's been reported that Microsoft CEO Steve Ballmer once pretended to stamp on an employees iPhone and that workers can only claim back expenses related to mobiles that run windows software.
