Purpose: The cellular operator industry in responding to the need for connectivity and digital services continues to evolve. Answering these challenges, Telkomsel as the largest operator in Indonesia continues to strive to provide the best service in the midst of competition. One of them is the youth segment as a great potential and in terms of market is still not dominant. In Central Jakarta, Telkomsel's youth market segment is still not dominant. The presence of by.U which specifically targets this segment is a solution to increase customers. In improving the market and competitiveness, companies develop marketing elements that are combined into a marketing mix. This study aims to determine how Telkomsel with by.U products affects consumer purchasing decisions through a marketing mix consisting of product, price, place, promotion, people, process, and physical evidence.   Method: This research uses quantitative methods, namely conducting research through data collection using questionnaires. The data analysis technique used is partial least square structural equation modeling with SmartPLS software. Results: In this study, 7Ps elements in the marketing mix that have a positive and significant effect on purchase intention, namely price, promotion, people, and process. In addition, the moderating variables in this study, namely the level of education and student pocket money, also have a positive and significant effect. So that to increase the market with the by.U product, Telkomsel must continue to pay attention to strategies related to promotion and price, especially discounts and promotional materials that exist both offline and online. It was also found that the need for internet service quality by.U should be a special concern for companies to answer the need for videos, music, and games.