other two countries in developing mobile data services. Although the technologies have not been well developed in China, the mobile data services have gained a high prevalence among Chinese mobile subscribers. In South Korea, with strong manufacturing and mobile service technologies, diverse mobile services are provided for customers. Comparative Study on the Mobile Data Service Development Compared to the operators in China and South Korea, the U.S. MNOs kind of ignored mobile data services in the early stage. In the depression period of the U.S. telecom industry they chose to put more attention on the low-risk voice services under the pressure of competition, while China and South Korea put mobile data services into an important strategic position and began to prepare from technology to market to expand this new market. Especially in South Korea, mobile techno- logy and service industry has important position in the national strategy. The strong support from the government made it leading in the world both in terms of tech- nology and service development. Mobile data services can be a strong element in improving the international competitiveness. The value chain strategy is very important in developing mobile data services. The experience from China showed that a keystone ecosystem strategy to foster a healthy ecosystem has gained considerable achievement in developing mobile data services. Effective partner relationship management and active innovations are major success factors in it. The cooperation among MNOs, SPs, and CPs has expanded the contents and applications of mobile data services greatly. Mobile data service could become a big industry and play an extremely important role in the economy. Some traditional industries' business model may change with the usage of mobile data services. For a large market, to be open for the development of con- tents and applications will promote growth greatly. Compared to the keystone strategy, the U.S. operators' walled-garden strategy is a restricting factor for mobi