AT&T INC.

Our key suppliers include AT&T, Avaya, Axis, Cisco, Comcast Business, Dell, Elo, Extreme, Five9, Fortinet, Hanwha, Honeywell, HP Poly, HPE/Aruba, HPE/Juniper, Ingenico, Lumen, Microsoft, NiCE, RingCentral, Ubiquiti, Verifone, Verizon, Zebra Technologies and Zoom.

For the three months ended March 31, 2025, the Datacom JV owned cell towers located in Texas, Wisconsin, New York, Missouri and Florida that account for approximately 11.1%, 13.3%, 12.5%, 11.7% and 8.7%, respectively, of total cell tower rental revenue.For the three months ended March 31, 2026, cell tower leases with tenants under common control of Verizon Communications Inc., AT&T Inc., T-Mobile USA, Inc. and US Cellular accounted for approximately 31.4%, 18.0%, 16.5% and 7.8 %, respectively, of total Datacom JV cell tower revenue.

For the year ended December 31, 2024, the Datacom JV owned cell towers located in New York, Florida, Missouri, and Texas that account for approximately 16.48%, 11.01%, 12.52%, and 14.45%, respectively, of total cell tower rental revenue.For the year ended December 31, 2025, cell tower leases with tenants under common control of Verizon Communications Inc., AT&T Inc., US Cellular and T-Mobile USA, Inc. accounted for approximately 31.07%, 18.46%, 8.33% and 14.12 %, respectively, of total Datacom JV cell tower revenue.

For the three months ended March 31, 2025, cell tower leases with tenants under common control of Verizon Communications Inc., AT&T Inc., T-Mobile USA, Inc. and US Cellular accounted for approximately 31.5%, 18.7%, 11.4%. and 8.8%, respectively, of Datacom JV total cell tower revenue.As a Lessee The Datacom JV is a lessee for certain properties, including ground leases.

For the year ended December 31, 2025, our top four customers by total revenue were T-Mobile (18%), AT&T (17%), Verizon Wireless (14%) and Telefónica (10%).

(1) On February 2, 2026, AT&T Inc. completed its acquisition of substantially all of the mass markets fiber business from Lumen Technologies Inc. As a result, amounts reported for AT&T Inc. in the current fiscal year include revenues from the mass markets fiber business to the extent they have transferred from Lumen Technologies Inc.

AT&T Inc. (1) $ 403.8 20.6 % $ 325.1 25.8 %

During fiscal 2026, we derived approximately 25.4% of our total contract revenues from AT&T Inc., 14.0% from Verizon Communications, Inc. and 10.8% from Lumen Technologies Inc. Revenues for Verizon Communications, Inc. includes revenue attributable to Frontier Communications Corporation retrospectively for all periods presented as a result of its acquisition by Verizon Communications, Inc. on January 20, 2026.

AT&T Inc. $ 361.9 24.9 % $ 265.6 20.9 % $ 1,060.0 25.9 % $ 691.3 19.1 %

AT&T, Inc. (1) 25.4% 20.1% 16.9%

Sales to AT&T were $500.7 million, or 10.5% of total revenue, in fiscal 2025, and $475.3 million, or 11.8% of total revenue, in fiscal 2024.

AT&T is a customer of Ciena; see Note 2 above.

AT&T is a customer of Ciena; see Note 2 above.

• Satellite Modems and Amplifiers: A leading U.S.-based provider of satellite modems and high-power amplifiers, facilitating the transmission of voice, video and data over GEO, MEO and LEO satellite constellations • Troposcatter Technologies: A global leader in troposcatter technologies, capable of securely transmitting digitized voice, video, and data over distances up to 200 miles, with strong market share in existing C-band and X-band troposcatter systems worldwide • Cybersecurity Training (Formerly known as Government Services) : Provide advanced cybersecurity training, primarily in support of U.S. Government and certain commercial and university customers based on mature and proven training tools and programming • Space Components: Specializes in delivering components for antennas and high-reliability electronic components and engineering services for space programs • Customers include the world’s largest defense contractors, allied foreign governments, as well as multiple U.S. government agencies (including all branches of the U.S. Armed Forces) • Next-Generation 911 Solutions: we provide emergency call routing, location validation, network, policy-based routing rules, logging and security functionality to states and local governments • Global Carrier Location and Messaging Services: Software and equipment for location-based and text messaging services for carriers, including for public safety, commercial and government services, and wireless emergency alerts solutions for network operators • Call-Handling Solutions: we provide comprehensive 911 call handling applications for Public Safety Answering Points ("PSAPs") • Customers include state and local governments across the U.S., Canada and Australia, and several of the largest telecommunications companies in the world (including Verizon, AT&T, Nokia and Vodafone)

On May 21, 2025, we and certain of our affiliates entered into a definitive agreement to sell to AT&T the Lumen Mass Markets Fiber-to-the-Home business, operated by us and certain of our affiliates in 11 states (the "Territory") for $5.75 billion in cash, subject to working capital and other negotiated purchase price adjustments.

● the loss of significant customers, including AT&T and Verizon Wireless;

Examples of our customers include Advanced Micro Devices, Inc., América Móvil, AT&T Inc., British Telecom Openreach, Ciena, Cisco Systems, Inc., Deutsche Telekom AG, Ericsson, Lumen Technologies, Inc., Nokia Corporation and Verizon Communications Inc.