Japanese mobile carrier NTT DOCOMO plans to launch high-quality voice and video calls using Voice-over-LTE (VoLTE) technology on its LTE network, beginning late June. Four smartphones and two tablets in DOCOMO's summer lineup will become compatible with the new service after a software update scheduled in or after late June.

The service will enable users to receive Area Mail disaster-information notifications while making VoLTE voice/video calls. Also, users will be able to access high-speed LTE data communication during VoLTE voice calls.

DOCOMO's new VoLTE service will require a subscription to its LTE service Xi. Existing Xi billing plans, packet flat-rate services, discounts and dialing charges will be applicable to VoLTE voice calls, including the new Kake-hodai & Pake-aeru billing plans for flat-rate voice and data, as well as data sharing with family members. Packet communication charges for VoLTE video calls will be offered free of charge until September 2015, after which video calls will incur both voice and packet communication charges.