This case addresses how SK Telecom, as a market leaser in the matured market with high competition, has achieved the success by creating TTL concepts and products. Through the investigating of the leading company's marketing problem of differentiation of commodity service like SK Telecom, the case highlights the importance of differentiation which can lead the company to the competitive advantage. The key idea implied by the TTL case is based on the concept and a kind of culture community of target customers through the differentiation by various attempts. This case also addresses how to respond to maintain and keep the previous success over time.