Telecommunications companies use various technologies to transmit information globally. Some of the largest companies in the telecommunications sector provide fixed-line telephone and wireless services, as well as Internet data and video communications.

The telecommunications sector is changing rapidly. Traditional technologies such as wireline telephone, radio, and television once dominated the telecommunications universe, but wireless mobile and Internet technology are quickly becoming the new norm.

On Nov. 12, 2020, President Donald Trump signed an executive order forbidding U.S. investors from investing in companies that he designated "Communist Chinese military companies." The ban takes effect at 9:30 a.m. on Jan. 11, 2021 and currently includes 31 companies listed here.

These are the 10 biggest telecommunications companies by 12-month trailing (TTM) revenue. This list is limited to companies that are publicly traded in the U.S. or Canada, either directly or through ADRs. Some companies outside the U.S. report profits semi-annually instead of quarterly, so the 12-month trailing data may be older than it is for companies that report quarterly. Data is courtesy of YCharts.com. All figures are as of August 3.

Some of the stocks below are only traded over-the-counter (OTC) in the U.S., not on exchanges. Trading OTC stocks often carries higher trading costs than trading stocks on exchanges. This can lower or even outweigh potential returns.

#1 AT&T Inc. (T)

  • Revenue (TTM): $175.1 billion
  • Net Income (TTM): $12.0 billion
  • Market Cap: $210.8 billion
  • 1-Year Trailing Total Return: -7.6%
  • Exchange: New York Stock Exchange

AT&T is a holding company that provides communications and digital entertainment services globally. Its services and products include wireless communications, data/broadband and Internet services, digital video services, local and long-distance telephone services, telecommunications equipment, managed networking, and feature film, television, and gaming production and distribution. The company also owns and operates regional TV sports networks.

#2 Verizon Communications Inc. (VZ)

  • Revenue (TTM): $129.7 billion
  • Net Income (TTM): $19.1 billion
  • Market Cap: $237.9 billion
  • 1-Year Trailing Total Return: 8.5%
  • Exchange: New York Stock Exchange

Verizon Communications is a holding company that provides communications, information, and entertainment products and services. It offers wireless voice and data services and equipment sales, as well as data and video communications products and services, such as broadband video, data center and cloud services, security and managed network services, and local and long distance voice services.

#3 Nippon Telegraph & Telephone Corp. (NTTYY)

  • Revenue (TTM): $109.5 billion
  • Net Income (TTM): $7.9 billion
  • Market Cap: $84.1 billion
  • 1-Year Trailing Total Return: 6.0%
  • Exchange: OTC

Nippon Telegraph & Telephone is a Japan-based holding company that provides telecommunication services. It offers domestic intra-prefectural communication services, such as fixed voice-related, Internet Protocol (IP), and packet communications services, and sells telecommunications equipment. The company also provides mobile voice-related, IP, and packet communications services, as well as system integration and network system services. Additionally, Nippon operates businesses in real estate, finance, and more.

#4 China Mobile Ltd. (CHL)

  • Revenue (TTM): $107.7 billion
  • Net Income (TTM): $15.4 billion
  • Market Cap: $139.5 billion
  • 1-Year Trailing Total Return: -15.6%
  • Exchange: New York Stock Exchange

China Mobile is a China-based investment holding company primarily engaged in telecommunication and related businesses. The company offers voice services for local calls, domestic and international long distance calls, and roaming services. It also provides short message and multimedia message services, wireless data traffic, application, and information services. China Mobile also provides wireline broadband and related services. This company is on the list of "Communist Chinese military companies," included in President Trump's executive order above.

#5 Deutsche Telekom AG (DTEGY)

  • Revenue (TTM): $89.7 billion
  • Net Income (TTM): $4.3 billion
  • Market Cap: $79.0 billion
  • 1-Year Trailing Total Return: 6.1%
  • Exchange: OTC

Deutsche Telekom is a Germany-based provider of telecommunications and information technology services. The company offers fixed-line telephone services, mobile communications services, Internet access, and combined information technology and telecommunications services to customers in Germany, Eastern Europe, and the U.S.

#6 SoftBank Group Corp. (SFTBY)

  • Revenue (TTM): $57.0 billion
  • Net Income (TTM): -$9.0 billion
  • Market Cap: $123.4 billion
  • 1-Year Trailing Total Return: 24.1%
  • Exchange: OTC

SoftBank Group is a Japan-based holding company principally engaged in communication and Internet related businesses. The company provides mobile terminals, mobile communication services, fixed communication services, and PC software. SoftBank Group also operates online advertising and e-commerce businesses, designs IP and related technologies for microprocessors, and sells various software tools.

#7 China Telecom Corp Ltd. (CHA)

  • Revenue (TTM): $53.8 billion
  • Net Income (TTM): $2.9 billion
  • Market Cap: $24.0 billion
  • 1-Year Trailing Total Return: -30.3%
  • Exchange: New York Stock Exchange

China Telecom is a China-based provider of wireless and mobile telecommunications. Its products and services include voice, Internet, telecommunications network resource services, network equipment leasing, and information and application services. This company is on the list of "Communist Chinese military companies," included in President Trump's executive order above.

#8 Telefonica SA (TEF)

  • Revenue (TTM): $50.9 billion
  • Net Income (TTM): $199.8 million
  • Market Cap: $22.1 billion
  • 1-Year Trailing Total Return: -40.6%
  • Exchange: New York Stock Exchange

Telefonica is a Spain-based multinational integrated and diversified telecommunications group. The company is engaged in activities related to wireline, wireless, cable, data, Internet, and television businesses. Telefonica offers fixed telecommunication, Internet and broadband multimedia, and digital services such as Internet of Things (IoT).

#9 Vodafone Group PLC (VOD)

  • Revenue (TTM): $49.8 billion
  • Net Income (TTM): -$1.0 billion
  • Market Cap: $40.8 billion
  • 1-Year Trailing Total Return: -11.4%
  • Exchange: NASDAQ

Vodafone Group is a U.K.-based company that provides a range of telecommunications services, including voice and data communications. It offers mobile services, such as call, text, and data access, as well as fixed line services, including broadband, television, and voice. The company also offers IoT, public and private cloud services, cloud-based applications, and products for securing networks and devices.

#10 America Movil SAB de CV (AMX)

  • Revenue (TTM): $49.8 billion
  • Net Income (TTM): $1.1 billion
  • Market Cap: $55.0 billion
  • 1-Year Trailing Total Return: -7.5%
  • Exchange: New York Stock Exchange

America Movil is a Mexico-based provider of telecommunications services to customers worldwide. The company offers wireless voice, wireless data, fixed voice, fixed broadband, fixed data, pay television, and information technology services.