Nokia was the world's largest cell phone maker, selling billions of devices from the 1990s to the beginning of the 2010s. They also ruled the growing smartphone niche with Symbian. However, the introduction of iPhone and Android made clear that Symbian was getting outdated, and their MeeGo project was slow to deliver a modern successor. In panic, they made the mistake of hiring an ex-Microsoft CEO, who instead pushed for a financially catastrophic migration to Windows Phone. Nokia has since sold their handset unit to Microsoft, but remains a major provider of telecom infrastructure equipments.