T-Mobile USA, Inc. 601 Pennsylvania Avenue, Washington, DC 20004 November 19, 2018 Hon. Ajit V. Pai Chairman Federal Communications Commission 445 12th Street, SW Washington, DC 20554 Dear Chairman Pai: Thank you for your letter to our CEO, John Legere, regarding T-Mobile s efforts to end caller ID spoofing. Our customers hate fraudulent calls, and so do we. As the Un-carrier, T-Mobile has been leading the industry to combat this problem we have already blocked over a billion scam calls and have immediate plans to do even more to spare our customers from unwanted robocalls and fraud. T-Mobile recently announced that we are the first carrier that is ready today to deploy the industry-developed call-authentication system to ensure that all the calls we originate are appropriately signed.1 And we are the first to announce that we are ready today to peer with others that have adopted the FCC-recommended SHAKEN/STIR standards.2 We look forward to adoption of the standards throughout the industry so that we can notify customers that the calls they are receiving are verified as authentic, and not spoofed or hijacked. You have asked specifically what type of information we intend to provide to customers to identify improperly signed or unsigned calls once SHAKEN/STIR is deployed and handset specifications include the requirements to support the standards. We are still considering various options, but for authenticated calls, it is likely that we will opt for a  call verified notification. We also have recently announced the integration of new spoof identification technology at the network level to enhance our existing free scam detection services Scam ID and Scam Block. Scam ID instantly alerts customers when an incoming call is likely a scam, 1 See T-Mobile Has Blocked Over a Billion Scam Calls, and Now Industry-Leading Tech Keeps Customers Even Safer T-MOBILE, (Nov. 8, 2018), https://www.t-mobile.com/news/t-mobile- fights-scam-calls. 2 Id. Hon. Ajit V. Pai November 19, 2018 Page 2 and Scam Block lets customers choose to block scam calls automatically before they reach their devices. Since launching Scam ID and Scam Block 18 months ago, we have tagged over six billion calls as Scam Likely and, as mentioned above, blocked over one billion scam calls. Our recent improvements offer new protections against increasingly common  neighborhood spoofing, whereby scammers temporarily hijack a phone number to match the area code and three-digit prefix of the person they are targeting, making the incoming call look familiar. Existing consumer protection applications only black-list against known scam numbers, not legitimate numbers that have been temporarily hijacked by scammers. We identify these hijacked numbers by analyzing the call details for a potential scam call before it reaches a customer s phone. We are proud of being the industry leader on scam identification and blocking and look forward to continuing to work with you and the Commission in the fight to protect American consumers against scam calls. Sincerely, Kathleen O Brien Ham, Senior Vice President, Government Affairs cc: Deborah.Salons@fcc.gov (by e-mail) WC Docket No. 17-97 (via ECFS)