Microsoft will have to work quickly to counter this threat, according to Winton. Although the company sold approximately four million cellphones with Windows Mobile in 2006, an increase from two million in 2005, Winton estimates that many of these were replacement units for their buyers, and so the total number of Windows Mobile phones in use should be no more than seven million. Apple hopes to have sold 10 million phones by the end of 2008 alone, which could immediately reduce Microsoft to second place.