Nippon Telegraph and Telephone (NTT) DoCoMo, Inc., where "DoCoMo" is shorthand for "Do Communications Over the Mobile Network" as well as a play on "dokomo," the Japanese word for "everywhere," is the most prominent wireless telecommunications operator in Japan, with more than 50 million subscribers.

In August 1991, it was inaugurated as a subsidiary of NTT to take over the mobile phone operations. DoCoMo offers the following services: phone, video phone, i-mode (internet) and mail (i-mode mail, Short Mail, and SMS). Also among the businesses of DoCoMo are paging, satellite, and personal handy-phone system (PHS, under the brand name Paldio).

The company provides Digital Mova, its brand of second generation (2G) personal digital cellular (PDC) services operating in 800 MHz and 1.5 GHz bands with a total of 34 MHz bandwidth, and Freedom of Mobile Multimedia Access (FOMA), DoCoMo’s brand of third generation (3G) wideband code-division multiple access (W-CDMA) services operating in the 2 GHz (1945-1960 MHz) band at a data transmission rate of 384 kbps.

In order to upgrade the data rates towards 14.4 Mbps, DoCoMo is planning to use High-Speed Downlink Packet Access (HSDPA).

DoCoMo has a proprietary mobile internet platform known as i-mode, which as of October 2006 had 47 million customers in Japan alone. It offers mobile phone users the benefits including mobile reservations, secure wireless transactions, updates on the latest information, easy access to thousands of online websites and specialized services such as email, online shopping, mobile banking, restaurant reviews and ticket reservations.

Websites are accessible to mobile users from anywhere in Japan at remarkably inexpensive rates, since charges are based on the volume of data transmitted instead of airtime.

Unlike most mobile operators, DoCoMo dedicates extensive effort to research and development (R & D). Its strong investment in R & D largely helped in allowing DoCoMo to introduce i-mode data services and 3G communications services long before these services were introduced by any other wireless telecommunications company in the world.

Outside of Japan, DoCoMo has a wide range of foreign investments, although the company was not successful in investing in foreign carriers. DoCoMo had invested billions of dollars in Hutchison Telecom, KTF and AT&T Wireless, and subsequently booked a total loss of around US$10 billion, although the operations of DoCoMo in Japan were profitable.