Global smartphone sales volume will grow +1% YoY in 2018, improving slightly from 2017. Android will maintain its dominant position in global smartphone OS market, followed by iOS. Tizen's momentum has been softened, after Samsung has shifted its OS efforts from smartphone to IoT devices. In addition, we expect a new operating system is potentially to emerge in 2020 when 5G starts to take off. Our extensive report forecasts global smartphone sales, by 14 operating systems, for 88 countries worldwide, from 2007 to 2023. Almost every major country worldwide is covered, including United States, China, India, Indonesia, Japan, South Korea, Russia, Brazil, Mexico, South Africa, Saudi Arabia, UK, Germany, France, Italy and Spain. This report can be used by operators, software developers, content developers, handset vendors, component makers, car manufacturers and other stakeholders to determine the size and growth rate of the huge global smartphone OS market.