A report published fresh this week by research firm International Data Corporation (IDC) predicts that 2013 will be the first year in which smartphones outsell feature phones at a global level.

Though a victory, it won't be by much as the the report indicated smartphone sales in 2013 will hit 918.6 million units. IDC said this will be just 50.1 percent of total handset shipments made worldwide.

That's a razor thin lead and means smartphones will squeak by if IDC's prediction comes true.

The research firm took its forecast four years further, as well, predicting that current trends will see smartphones take two thirds of the global mobile phone market in 2017, with 1.5 billion shipping by the end of that year.

What trends?

IDC's forecasts are based on some easily identifiable trends.

For one thing, the report noted smartphone prices keep going down globally.

Potential smartphone users have more options than ever to choose from as well, and 4G penetration is improving worldwide.

Finally, developing and emerging markets will play a larger role in smartphone growth over the next four years than more "mature economies" like the U.S., IDC explained.

In those markets, smartphone adoption is still relatively light, but "economic prospects are considerably higher" than in the U.S. and similar economies. The middle class in these countries too is prepared to start buying more smartphones.

This includes Brazil, with 3.1 percent of the global smartphone market in 2013 and 4.4 percent by 2017. India, meanwhile, will hit 3 percent in 2013 and 10.3 percent by 2017, the firm predicted.

China will remain the largest market for smartphones, but it's expected to drop slightly from 32.8 percent of the market in 2013 to 30.2 percent by the end of 2017.

The report also predicted that Japan will fall from 3.8 percent of the global smartphone market in 2013 to 2.5 percent in 2017, the U.K. will fall from 3.9 percent to 3.1 percent, and the U.S. from 15 percent to 12.1 percent, as developing economies gobble up more market share.

The rest of the world collectively is forecast to drop from 38.4 percent of total smartphones in 2013 to 37.5 percent by the end of 2017.

The rise of China

IDC reported that China overtook the U.S. last year with the most smartphone shipments of any market globally.

"While we don't expect China's smartphone growth to maintain the pace of a runaway train as it has over the last two years, there continue to be big drivers to keep the market growing," said IDC Asia/Pacific's senior research manager, Melissa Chau, in the report.

Those "drivers" include China's adoption of 4G networks. Chau added that although smartphone shipments in India are expected to stay under 50 percent even through 2017, the country will nevertheless become the third largest market globally in 2017.

Feature phones still accounted for 58 percent of handsets worldwide in 2012, but that number will go from a predicted 49.9 percent in 2013 to 33.6 percent by the end of 2017, according to IDC.