NTT - DoCoMo is one of the major providers here in Japan. The others being AU and Softbank. Having said that there are lots of new entrants who offer cheaper rates than the incumbents. They ride on the signal of the major players. I guess its kind of win-win for all. But the rates I pay is close to $10/GB. Unlimited rate for those who are ready to pay $50 or more per month ( not sure about the current rates. Could be a bit outdated)