Japanese number one operator NTT Docomo said it had signed up more than three million subscribers for its Xi-branded LTE service, which was initially launched in December 2010.

The company said that the service had hit the one million milestone one year later, with the next two million achieved in less than six months.

It noted that subscriptions have “continued to increase with the introduction of the first Xi-compatible smartphones in November 2011 and a series of popular marketing campaigns.”

Looking forward, Docomo said that it is looking to offer new Xi-compatible smartphones, mobile Wi-Fi routers and other devices, as well as “beneficial services” such as free Xi-to-Xi voice calls.

The company has previously stated a target of 30 million LTE connections by the year to March 2016.

According to Wireless Intelligence figures, there are currently more than 17 million LTE subscriptions globally, of which just over 6 million are in APAC. Japan is second to South Korea in this region.

The US currently leads the way overall, with nearly 10 million LTE connections, driven by the fact that market leaders Verizon Wireless and AT&T support the technology.