Some China-based white-box vendors launched tablets with built-in 3G modules to allow voice communications, in China and Southeast Asia in early 2014 and saw good sales performance, but have faced strong competition from brand vendors which have also launched low-cost tablets with phone functions such as Samsung Electronics and Lenovo, according to China-based white-box vendors.

Currently, Lenovo is offering its 7-inch A3000 tablet with phone in China at CNY880, while Samsung's Galaxy P3100 is selling for CNY1,100 in the country. The two products have gained strong popularity because of their attractive prices.

As for China-based white-box vendors, Colorfly's G80 and Cube's Talk tablets also enjoy strong demand due to their friendly prices of CNY499 and CNY399.

However, as competition is growing fiercer in the Asia Pacific region, white-box vendors have started looking to enter other regions.

In the second quarter, tablet sales in the Asia Pacific region excluding Japan were 13.8 million units with models with phone functions accounting for almost 25%, up from 12-16% in previous quarters, the sources noted citing IDC figures.