Nokia today posted a surprisingly mixed first quarter, as the New York Times reports. The struggling Finnish handset manufacturer sold 5.6 million Lumia phones during the period, up from 4.4 million in the previous quarter, and predicted even stronger sales for the second quarter. But it posted a 20 percent decline in revenue over the same period a year ago, with overall handset shipments falling 21 percent — a dip far steeper than analysts had predicted.

That dip can be traced to the low- and mid-range feature phones that have become Nokia’s safety net as it continues its difficult transition from its own Symbian operating system to Windows Phone, as Forbes notes. And it stems from the fact that emerging markets have become the latest battleground in the handset wars, with everyone from BlackBerry to Samsung to countless manufacturers of affordable Android gadgets vying for a piece of the pie. If Nokia continues to lose traction there, it will need to ramp up its Windows Phone business in a big hurry.