Worldwide smartphone sales increased by nearly 4 percent in the recent quarter, but Microsoft's Windows Phone OS failed to capitalize on the growth and dropped below 1 percent market share. Gartner's latest smartphone sales report provides the latest proof of the obvious: Windows Phone is dead. Gartner estimates that nearly 2.4 million Windows Phones were sold in the latest quarter, around 0.7 percent market share overall. That's a decrease from the 2.5 percent market share of Windows Phone back in Q1 2015.

We might have seen the last Lumia already

The drop in sales is primarily driven by Microsoft's lack of new Lumia devices. Microsoft revealed its plans to sell its feature phone business to a Foxconn subsidiary for $350 million last week, and the company hinted that we might have seen the last Lumia-branded smartphone. Microsoft only sold 2.3 million Lumia devices in the latest quarter, a massive 73 percent drop from the 8.6 million in the same period last year. As a result, Microsoft's revenue from phones declined 46 percent. Rumors suggest Microsoft may be considering a Surface-branded phone for 2017.

If Gartner's estimates are accurate, then Microsoft sold 2.3 million of the 2.4 million Windows Phones in the recent quarter. If Microsoft has no plans to introduce new Lumias this year then the drop in both sales and market share will continue. Microsoft appears to be leaving Windows Phone up to other phone makers to support, but the company currently controls more than 95 percent of all Windows Phone sales with its Lumia devices. It's unlikely that other phone makers, that have typically ignored Windows Phone, will have any impact on Microsoft's mobile OS market share as a result.

Nokia Lumia 650