Beancounters at Big G say that the market is now saturated and sales have declined.

Worldwide smartphone sales recorded the slowest growth rate since 2013 in the second quarter of 2015. Worldwide sales of smartphones to end users totalled 330 million units, an increase of 13.5 percent over the same period in 2014.

Anshul Gupta, research director at Gartner. Emerging Asia/Pacific (excluding China), Eastern Europe and Middle East and Africa were the fastest-growing regions, driven by good performance from Chinese and local vendors. Smartphone sales in China fell for the first time year over year, recording a 4 percent decline.

"China is the biggest country for smartphone sales, representing 30 percent of total sales of smartphones in the second quarter of 2015. Its poor performance negatively affected the performance of the mobile phone market in the second quarter," said Gupta.

"China has reached saturation — its phone market is essentially driven by replacement, with fewer first-time buyers. Beyond the lower-end phone segment, the appeal of premium smartphones will be key for vendors to attract upgrades and to maintain or grow their market share in China."

Despite the launch of new S6 models, Samsung's premium phones continued to be challenged by Apple's large-screen iPhones. Samsung lost 4.3 percentage points in market share and declined 5.3 percent in unit sales in the second quarter of 2015.

Huawei recorded the highest sales growth rate of 46.3 percent, thanks to strong overseas sales and 4G smartphone sales in China. iPhone sales increased 36 percent, which helped Apple gain 2.4 percentage points in market share.

Apple recorded strong iPhone replacements in both emerging and mature markets — and particularly in China. Total iPhone sales in China grew 68 percent to 11.9 million units.

Worldwide Mobile Phone Sales to End Users by Vendor in 2Q15 (Thousands of Units)

Source: Gartner (August 2015)