Japan’s mobile operator NTT DOCOMO has announced that subscribers to its Xi LTE mobile service surpassed two million on March 18. Xi launched on December 24, 2010 and reached one million subscribers one year later on December 25, 2011. Since then, subscriptions have doubled to two million in just three months, propelled by the introduction of the first Xi-compatible smartphones in November 2011.

Going forward, subscribers are expected to grow as DOCOMO continues to introduce additional Xi-compatible smartphones, tablets and data-communication devices and mobile Wi-Fi routers, as well as beneficial services, such as Xi Talk 24, which enables free, unlimited voice calls between DOCOMO users of Xi-compatible smartphones.