The Galaxy S III smartphones hit the shelves in countries including France and Britain. By the end of July, nearly 300 mobile operators around the world will be selling the device.
Samsung said the initial response to the new smartphone was positive. At Vodafone Group, pre-sale orders for the Galaxy S III outstripped those of any previous Android-based smartphones, according to Samsung.
The Galaxy series of smartphones is widely acknowledged in the industry as a success for Samsung, turning it from a smartphone also-ran into a viable competitor with the iPhone from Apple Inc.
While Apple has kept the screen size of the iPhone the same in every upgrade since 2007, Samsung increased the screen size of its highest-end smartphone in its two major updates. The latest Galaxy phone screen is nearly twice as big as the iPhone screen.
The 4.8-inch S III also features more computing power that supports voice commands and an eye-movement tracking feature to keep the screen from dimming.
Samsung overtook Apple in smartphone sales for the first time in the first three months of this year, according to research firm Strategy Analytics. The Suwon, South Korea-based company sold 44.5 million smartphones in the January-March quarter, compared with Apple's 35.1 million iPhone sales.
Market watchers expect that Apple may use its annual conference for developers next month to announce the yearly upgrade to the iPhone, which then can go on sale as early as July.
Aside from being big rivals in the smartphone market, Samsung and Apple have also a close business relationship. Samsung supplies mobile chips and display panels for iPhones and iPad tablet computers, counting Apple among its biggest clients.