Smartphone shipments to the world's biggest market, China, have contracted for the first time in six years, according to market research firm IDC.
The number of smartphones shipped fell by 4% from a year ago to 98.8 million units in the January to March period.
Between the last quarter of last year and the first quarter, shipments were down 8%, said IDC.
A build up of unsold stock is leading to a slowdown in the maturing Chinese mobile market, the firm said.
"China is often thought of as an emerging market but the reality is that the vast majority of phones sold in China today are smartphones, similar to other mature markets like the US, UK, Australia, and Japan," said Kitty Fok, managing director at IDC China.
"Just like these markets, convincing existing users as well as feature phone users to upgrade to new smartphones will now be the key to further growth in the China market."
Expansion
China surpassed the US to become the world's largest smartphone market in 2011.
IDC expects flat growth in Chinese market this year, adding that as the country's growth slows, Chinese manufacturers will focus on expanding in global markets such as India and South East Asia.
US tech giant Apple overtook China's Xiaomi in the first quarter to be the top smartphone provider in the country thanks to consumers' preferences for the larger screens of the latest iPhone models, according to IDC.
Apple now accounts for 14.7% of the market, compared with 13.7% for Xiaomi.
The Chinese smartphone maker, meanwhile, has said it is focusing on expanding abroad.
In April, India's Ratan Tata, the chairman emeritus of the Tata conglomerate, bought a stake in Xiaomi - a move seen as part of the smartphone maker's bid to increase its presence in the world's third largest market.
By BBC NEWS
