Mobile communications market in Japan has expanded remarkably. The market expansion so far has been led by the growth of voice usage. However, voice usage will certainly saturate in the near future, simply because the population will not increase any more, and people's active hours in a day are limited. We are about to enter our next stage of growth, one driven by mobile multimedia service that can handle not only voice but also data and image communications. I'd like to introduce our "Challenging the Mobile Frontier" with showing the several examples such as "i-mode" and "IMT-2000".