Japan has 2 main telephone companies, NTT and KDDI. There are 3 mobile phones companies : NTT-Docomo, KDDI AU and the British newcomer Vodafone, who acquired J-phone in 2003. NTT still dominates the hard-line phonemarket, while AU and Vodaphone are slowly gaining a larger share of the mobile phone market. But Docomo is still first.
Note that price agreements exist between those three mobile phone companies, although this is by no way unique to Japan. But competition is further hampered by the obligation for customers to register with a carrier while buying a phone, and the impossibilty to change carrier using the same phone afterwards (Japanese mobiles do not have cards inside, which can be changed to another phone).
