Microsoft is selling more Lumia smartphones and signed new Windows Phone licensing deals recently, but its mobile platform hasn't kept pace with rivals in key markets.

It's still early days for Microsoft's new handset business following its acquisition of Nokia devices in April. The company this week reported Lumia shipments of 9.3 million for its first quarter of 2015 — a figure that exceeds shipments of Lumia phones for all quarters under Nokia .

Despite selling more devices overall, Windows Phone hasn't enjoyed the same share of smartphone sales that it did under Nokia: the OS's share peaked in 2013 at just over 10 percent before dipping to 8.1 percent in the three months to the end of March of 2014 — up year on year but down from the previous quarter, according to figures by Kantar Worldpanel ComTech.

A similar pattern has played out in three months to September 2014, with Kantar reporting today that Windows Phone had a 9.2 percent share of sales in Europe's big five countries: Germany, Great Britain, France, Italy and Spain. The figure is down 0.3 percentage points year on year.

For the period, Windows Phone accounted for 9.6 percent of all smartphones in Great Britain, 10.6 percent in France, 15.2 percent in Italy and three percent in Spain. Windows Phone saw small year on year declines across all markets except for Italy, where it was up 1.5 percentage points.

Microsoft continues to struggle in China, where Windows Phone accounts for just 0.4 percent of sales in the period, down from 3.2 percent a year ago. Basically though, its tiny share of sales has been consistently low over the past year as Android takes a bigger slice of the country's smartphone market, up from 80.4 percent a year ago to 83.4 percent in this period.

Xiaomi and Huawei are driving Android's growth in China, Kantar's strategic insight director Dominic Sunnebo told ZDNet. There, Xiaomi dominated in China with a 30 percent share of smartphone sales, followed by Samsung with an 18.4 percent share.

In the US, Windows Phone took 4.3 percent of sales in the quarter, down 0.3 percentage points on last year. The biggest mover in the US was Android, which grew 4.5 percentage points over the year to 61.8 percent, ahead of iOS, which declined 3.3 percentage points to 32.6 percent. Still, Kantar notes that smartphone sales have grown 35 percent over the past year in the US.

The period only contains a week of iPhone 6 and iPhone 6 Plus sales since the devices started shipping in the UK on 19 September followed a week later by other major markets in Europe. Nonetheless, across Europe's largest five markets, iOS was up 1.5 percentage points from 13.9 percent last year to 15.4 percent, while Android retained its dominance with its share up 1.4 percentage points from 72.5 percent last year to 73.9 percent.

"Apple has also experienced market share and volume increases across all major European markets, as well as in China and Australia, in part thanks to the launch of its new handsets. Across Europe’s top five markets, the iPhone 6 has outsold the larger iPhone 6 Plus by five-to-one," said Sunnebo.

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