Japan’s Ministry of Internal Affairs and Communications today announced plans to require that all new mobile devices be sold to consumers with the SIM card ‘unlocked’ beginning next May.

The move will allow consumers to sign up for mobile service on any of the country’s three major operators – NTT Docomo, KDDI and SoftBank – as well as the many MVNOs operating in Japan, which now account for less than five per cent of mobile users, Reuters said.

The government expects the introduction of unlocked devices to force the big three to offer more competitive mobile rates.

Reuters reported that Docomo, KDDI and SoftBank have reduced the price of basic flat-rate voice and data plans to about JPY6,500 ($59), but that is still high compared to a similar plan for about JPY2,200 from Rakuten, an MVNO.

Reuters quoted SMBC Friend Research Centre analyst Naoki Yokota as saying: “There will be a flow of customers going into MVNOs, as their share is currently very small but that will grow.”

The big three account for 88 per cent of the country’s 144 million mobile connections.