I'm not sure how they've worked it out, but Cisco has a registered trademark for IOS, which is their operating system for network equipment: http://www.cisco.com/en/US/products/ps6537/products_ios_sub_...

They use it under licence from Cisco. See: http://www.apple.com/legal/trademark/appletmlist.html

    IOS is a trademark or registered trademark of Cisco in the U.S. and other countries and is used under license.