Anyone wondering why smartphone vendors have been plugging resources into developing devices for emerging markets lately needs look no further than the latest projections from Ericsson. Reuters reports that Ericsson sees smartphone subscriptions quadrupling over the next five years to total 4.5 billion by the end of 2018. Ericsson last year forecasted that there would be around 3.3 billion smartphone subscriptions by 2018, so it seems that smartphone adoption in emerging markets is accelerating significantly. With billions of new potential customers at stake, it’s easy to see why Apple, Samsung, BlackBerry and Nokia are all ramping up production of low-cost devices for key markets such as China, India, Brazil and Nigeria so they can hopefully lock in users’ loyalty for years to come.