FEDERAL COMMUNICATIONS COMMISSION WASHINGTON, DC 20554 July 20, 2021 Shellie Blakeney Director, Federal Regulatory Affairs T-Mobile USA, Inc. 601 Pennsylvania Avenue NW, Suite 800 Washington, DC 20004 Re: Wireless Emergency Alert Performance in Upcoming Test Dear Ms. Blakeney: Wireless Emergency Alerts (WEA) provide important and potentially life-saving information to the public in the event of a natural disaster or other critical situation. As a WEA provider, T-Mobile plays a key role in the alerting process and provides a vital tool for emergency managers to help keep the public safe. Thank you for your voluntary participation in this important program. The development and implementation of WEA have been a product of cooperation and collaboration between the Federal Communications Commission, the Federal Emergency Management Agency (FEMA), and the wireless industry. Building upon this history of collaboration, the Federal Communications Commission’s Public Safety and Homeland Security Bureau seeks T-Mobile’s cooperation in evaluating WEA performance during the upcoming nationwide emergency alert test. WEA’s utility relies upon successful and timely delivery of alerts to the public. As the agency that establishes the technical requirements for both WEA and the Emergency Alert System, the Federal Communications Commission has an interest in continually improving the effectiveness of our nation’s alerting systems, including through understanding any gaps in WEA performance. Emergency responders and the public should be able to rely on our emergency alert systems with confidence when they need them most. The upcoming nationwide test of WEA on August 11, 2021, by FEMA, provides an opportunity for T-Mobile and the FCC to work together to evaluate WEA performance. Accordingly, the Public Safety and Homeland Security Bureau requests that T-Mobile provide, in writing, responses to the following inquiries regarding the performance of the nationwide WEA test on T-Mobile’s network. 1. Did T-Mobile receive the nationwide test message and transmit it to its subscribers in all geographic areas where T-Mobile is offering WEA coverage? 2. What were the values of the Sent Date/Time and the Effective Date/Time of FEMA’s test alert? 3. At what time (to the closest millisecond, if available) did T-Mobile’s gateway/Cell Broadcast Entity receive the alert from FEMA’s Integrated Public Alert and Warning System (IPAWS)? 4. At what time (to the closest millisecond, if available) did T-Mobile transmit the alert to subscribers? 5. How much time (to the closest millisecond, if available) did T-Mobile’s network require to complete each of the following steps? a. For the gateway/Cell Broadcast Entity to process and send the alert to the Cell Broadcast Center. 1 b. For the Cell Broadcast Center to process and send the alert to its Radio Network Controllers/Mobility Management Entities/Access and Mobility Function? c. For the Cell Radio Network Controllers/Mobility Management Entities to process and send the alert to its NodeBs/eNodeBs/gNBs? d. For the NodeBs/eNodeBs to process and send the alert to T-Mobile’s subscribers? 6. With what periodicity do T-Mobile’s NodeBs/eNodeBs/gNBs transmit messages to its subscribers (e.g., via Cell Broadcast Service messages or SystemInformationBlockType12 message segments in the case of 4G)? 7. Describe any differences in WEA performance, including differences related to timing, between T-Mobile’s 3G, 4G, and 5G networks on the day of the test. 8. How many times did T-Mobile’s network rebroadcast the test message? At what frequency and duration did T-Mobile’s network rebroadcast the test message? 9. Describe any complications with alert processing or transmission that T-Mobile observed or became aware of on the day of the WEA test that may have delayed or prevented one or more of its subscribers from receiving the test alert. 10. Describe any steps that T-Mobile has taken or is taking to address any complications identified above, or any other complications that arose during the test. 11. Describe any other efforts that T-Mobile conducted to observe and evaluate WEA performance during the test, including any efforts to determine whether consumer handsets successfully displayed the alert. Please provide your responses, in writing, by August 25, 2021 (or in the event that the test is conducted on the secondary test date of August 25, by September 8, 2021). The Bureau asks that T- Mobile please respond via the FCC’s Electronic Comment Filing System (ECFS) in PS Dockets 15-91 and 15-94.1 Comments may be filed electronically using the Internet by accessing ECFS: http://apps.fcc.gov/ecfs/. If you have any questions, please contact Erika Olsen, Acting Chief of the Cybersecurity and Communications Reliability Division, at Erika.Olsen@fcc.gov. 1 Parties wishing to file materials with a claim of confidentiality should follow the procedures set forth in Section 0.459 of the Commission’s rules. Casual claims of confidentiality are not accepted. Confidential submissions may not be filed via ECFS but rather should be filed with the Secretary’s Office following the procedures set forth in 47 CFR § 0.459. Redacted versions of confidential submissions may be filed via ECFS. Parties are advised that the FCC looks with disfavor on claims of confidentiality for entire documents. When a claim of confidentiality is made, a public, redacted version of the document should also be filed. 2 Thank you for your continued efforts to ensure that the public receives life-saving WEA messages. Sincerely, Lisa M. Fowlkes, Chief Public Safety and Homeland Security Bureau cc: Steve B. Sharkey Vice President, Government Affairs, Engineering and Technology Policy T-Mobile USA, Inc. 3