While Asustek Computer aims to ship between 17 million and 25 million smartphones in 2015, the company is expected to ship 20 million units based on its ODM orders scheduled for the second half of the year, according to Taiwan-based smartphone supply chain makers.

Asustek shipped eights million smartphones in the first half of 2015 and, following the launches of ZenFone 2 Laser, ZenFone 2 Deluxe and ZenFone Selfie, expects to ship six million units in the third quarter, the sources indicated. However, Asustek will struggle to attain the upper target of 25 million units for the whole year, the sources said.

Asustek will unveil ZenFones in Brazil on August 21 and expects to ship one million units in the market in 2015. The phones will be produced at Foxconn Electronics' local factory, the sources said.

HTC aims to ship 15 million smartphones in 2015 but may struggle, the sources indicated. Acer aims to ship at least five million smartphones in 2015, but is expected to ship 3.5 million units at most, the sources said.