There is increasing demand for inexpensive SIM-free smartphones in the Japan market and consequently ZenFone series models launched by Taiwan-based vendor Asustek Computer have been in booming sale and Japan-based smartphone vendors including Sony Mobile Communications, Sharp, Fujitsu and Kyocera have sought cooperation with Taiwan-based ODMs to develop and produce inexpensive SIM-free Android smartphones specifically for sale in the Japan market, according to Taiwan-based smartphone ODMs.

Taiwan-based smartphone ODMs are mainly Compal Electronics, Arima Communications, Foxconn Electronics, FIH Mobile, Qisda, Inventec, Pegatron and Wistron.

After Japan's Ministry of Internal Affairs and Communications canceled SIM-lock policy, many MVNOs (mobile virtual network operators) in Japan have launched many inexpensive SIM-free smartphones and Japan-based mobile telecom carriers, NTT DoCoMo, KDDI and SoftBank Mobile, under competitive pressure, have followed suit, the sources indicated.

Due to its ZenFone series, Asustek has become the third largest smartphone vendor in the Japan market next only to Apple and Sony Mobile, the sources said.

There have been more than 10 million MVNO subscribers in the Japan market and the number is expected to rise to 15 million, accounting for 10% of all mobile communication subscribers, the sources noted.