In 2011, Nokia and Microsoft began a partnership which created Nokia Lumia, a series of smartphones that use the Windows Phone operating system and was meant to replace Symbian as the OS on Nokia's smartphones. Not many of these phones were sold and because of this, Nokia was losing money. Finally, in 2013, Microsoft bought out Nokia's mobile phone business, which became a division of Microsoft called Microsoft Mobile. Microsoft continued to make feature phones with the Nokia brand, but began using the Microsoft brand for its Lumia smartphones. Nokia's other phones, including the Nokia X which used Android, were discontinued, or no longer made.