GRI Index GRI Index The table below sets out our responses to relevant Global Reporting Initiative (GRI) disclosures, including select material topics identified in collaboration with stakeholders as part of our 2021 ESG materiality assessment. Disclosure# Disclosure Topic 2021 Response Organizational Profile 102-1 Name of the organization T-Mobile US, Inc. 102-2 Activities, brands, products, and services T-Mobile 2021 Form 10-K Part I pages 5-7 102-3 Location of headquarters Bellevue, Washington and Overland Park, Kansas 102-4 Location of operations T-Mobile 2021 Form 10-K Part I pages 1, 8 102-5 Ownership and legal form T-Mobile 2021 Form 10-K Part I page 1 T-Mobile common stock is traded on the NASDAQ Stock Market LLC under the symbol “TMUS.” 102-6 Markets served T-Mobile 2021 Form 10-K Part I pages 5-7 102-7 Scale of the organization T-Mobile 2021 Form 10-K Part I pages 5-8; Part II pages 27, 32 102-8 Information on employees and other workers T-Mobile 2021 Form 10-K Part I page 8 102-9 Supply chain overview Our Procurement and Supply organization spends billions of dollars on products, goods, and services annually, procuring everything our company needs to run our business, from hardware and network equipment to software, spectrum assets, and transportation. Engaging with small, medium, and large suppliers across the globe, we work to provide access and opportunities for all our suppliers and grow a robust supply chain that reflects our diversity and values. We are a company committed to conducting our business in a socially, environmentally, and economically responsible manner. This commitment extends to our supply chain partners and the goods and services they provide. Our Supplier Code of Conduct and Responsible Sourcing Guidelines outline the policies and guidelines that govern our supply chain partnerships and sustainability performance is a contributing factor to how we award contracts. In 2020, we began working with EcoVadis to better evaluate our supply chain across four key areas: environmental, labor and human rights, ethics, and sustainable procurement. We have received assessments from suppliers representing approximately 38% of our sourceable spend. 2021 CORPORATE RESPONSIBILITY REPORT OUR PEOPLE OUR GOVERNANCE OUR COMMUNITIES THE ENVIRONMENT THE NUMBERS AND SMALL PRINT 71 OUR COMPANY