AT&T, Inc. (NYSE: T) is an American telecommunications company with a market capitalization of $236.8 billion as of April 2016. The company provides wholesale and retail customers with mobile, Internet, voice services and entertainment. AT&T operates three business segments: wireless, wireline and international. The company has up to 201 suppliers that provide it with innovative world-class technology through the provision of its products and services that are critical to its success meeting customers' requirements. AT&T has supplier quality programs in place to ensure industry best practices are met, as the company views the supply chain as a crucial business function. AT&T’s top five suppliers based on percentage of revenue are all located within the United States. AT&T has a small number of international suppliers in Canada, the United Kingdom, South Korea, France and several other countries.

Amdocs

Amdocs Ltd. (NASDAQ: DOX) is an American technology services company with a market capitalization of $8.7 billion as of April 2016. The company offers software solutions and services to communications, entertainment and media service providers. Amdocs supplies AT&T with products and services that include customer and revenue management, network control, networks function virtualization, centralized management and optimization, advertising and media operations support systems. The company also supplies testing, consulting and system integration services. Amdocs generates 34% of its revenue from AT&T. As of April 2016, the company's stock had a five-year annualized return of 15.9% and paid investors a yield of 1.34%.

Communications Systems

Communications Systems, Inc. (NASDAQ: JCS) is an American electronic technology company with a market capitalization of $61.6 million as of April 2016. The company offers physical connectivity infrastructure products and services for broadband networks. Communications Systems operates three business segments: shuttle, transition networks and JDL technologies. It supplies AT&T with products and services that include fiber optic connectors, interconnect devices and fiber cable assemblies. Communications Systems generates 33% of its revenue from AT&T. As of April 2016, Communications Systems' stock had a five-year annualized return of -7.67% and paid investors a healthy yield of 9.1%.

MasTec

MasTec, Inc. (NYSE: MTZ) is an American industrial services company with a market capitalization of $1.7 billion as of April 2016. The company offers engineering, building, installation, maintenance, and upgrades of utility and communications infrastructure. MasTec builds distribution systems and helps AT&T install fiber optic cable, coaxial cables and copper lines. MasTec generates 32% of its revenue from AT&T. As of April 2016, the company's stock had a five-year annualized return of -0.63%.

Inteliquent

Inteliquent, Inc. (NASDAQ: IQNT) is an American communications company with a market capitalization of $558 million as of April 2016. The company provides wholesale voice services for carriers and service providers. It supplies AT&T with voice telecommunications services utilizing an all-Internet protocol network that enables connectivity for various media types that include voice and video. This allows AT&T to provide voice traffic to customers in areas where its network is limited or nonexistent. Inteliquent generates 31% of its revenue from AT&T. As of April 2016, the company's stock had a five-year annualized return of 7.83% and paid investors a yield of 3.66%.

Crown Castle International

Crown Castle International Corporation (NYSE: CCI) is an American financial company with a market capitalization of $29.7 billion as of April 2016. The company owns, operates and leases infrastructure for wireless communications. Crown Castle International leases telecommunications towers and other infrastructure to AT&T. It also provides network services that relate to wireless infrastructure. Crown Castle International generates 27% of its revenue from AT&T. As of April 2016, Crown Castle International stock had a five-year annualized return of 17.15% and paid investors a yield of 4.02%.

Want to learn how to invest?

Get a free 10 week email series that will teach you how to start investing.

Delivered twice a week, straight to your inbox.