ample, the interaction with audience by SMS has become an important part of all the TV Contents and Point-to-point Games Ringtones Pictures Video applications communications Technological ...... platforms Contents and Banking Email Mobile applications Advertising Voting Figure 13.1 The categories of mobile data services. Service Delivery Platforms shows and radio broadcasting programs, and mobile music downloading has become a major channel for digital music distribution. In South Korea, multiple data service platforms technologies such as SMS, MAP (Mobile Application Part), WAP, and BREW are utilized for mobile data services. Based on the highest penetration rate of cell phones (over 90%) among three countries, the world-class wireless telecommunication infrastructure and the demanding and sensitive customers, over 250 kinds of application services were already available in the market in 2005 [7]. Although operators are pursuing almighty strategy, each of the CPs, operators, and handset companies, are still developing various applications such as music, game, multimedia, and informa- tion with their own technologies or cooperation among them. Currently, espe- cially, South Korea has many CPs that have highly competitive and unique mobile data service, and these companies are trying to make inroads into the world mar- ket independently or under support of operators. 13.3.2 Prevalence It is difficult to measure and compare the level of mobile data services development because of the high diversity of mobile data services. Different indicators are used in different countries. We try to find comparable data to show the prevalence of mobile data services in the three countries. The common data services as techno- logical platforms in the three countries are SMS, MMS, and mobile Internet access. Therefore, we use the three types of mobile data services as main indicators. According to the data from a survey of mobile subscribers ending at the begin- ning of 2007, it was estimated that in 2007 about 40% of U.S. mobile 