Who Are the Big Four Telecom Companies? How the Largest U.S. Carriers Connect Businesses in San Jose, CA
In the United States, the big four telecom companies were traditionally AT&T, Verizon, T-Mobile and Sprint, the four national wireless carriers. After T-Mobile merged with Sprint in 2020, only three national wireless carriers remained, so today’s lists usually name AT&T, Verizon and T-Mobile, plus Comcast when cable and broadband providers are included.
Which fourth company appears depends on whether a list focuses only on wireless or on telecom as a whole. Either way, these carriers provide much of the phone and internet service businesses rely on, while local firms such as a Telecommunications Contractor in San Jose, CA connect that service inside each building. This guide explains who’s in the big four, how the group has changed and what it means for businesses.
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For most of the 2000s and 2010s, the phrase “big four” described the four companies that ran nationwide wireless networks in the U.S.: AT&T, Verizon, T-Mobile and Sprint. Together they served the vast majority of mobile customers in the country.
That changed in April 2020, when T-Mobile completed its merger with Sprint. As part of the regulatory approval, DISH Network (later combined with EchoStar) received Sprint’s Boost Mobile brand and was expected to build a fourth national wireless network. In 2025, EchoStar agreed to sell major spectrum holdings and move Boost customers onto AT&T’s network, which further reduced its role as a fourth independent carrier.
As a result, many people now talk about the “big three” wireless carriers. When writers still say “big four,” they often add Comcast, one of the largest internet and cable providers in the country, which also sells wireless service through Xfinity Mobile.
Companies Usually Included in the Big Four
These are the companies you’ll most often see named, depending on the list.
- AT&T: wireless, fiber internet and business services, and the established local phone company in much of California
- Verizon: wireless, fiber and business services, and among the largest U.S. telecom companies by revenue
- T-Mobile: wireless and home internet, and larger since absorbing Sprint in 2020
- Comcast: cable internet, business services and Xfinity Mobile, often included in broader telecom lists
- Sprint: part of the original big four until its 2020 merger with T-Mobile
The Big Four Telecom Companies at a Glance
This table compares the companies that most often appear in big four lists.
| Company | Main services | Status |
|---|---|---|
| AT&T | Wireless, fiber internet, business networks | Current national carrier |
| Verizon | Wireless, fiber internet, business networks | Current national carrier |
| T-Mobile | Wireless, home internet, business services | Current national carrier; merged with Sprint in 2020 |
| Comcast | Cable internet, business services, Xfinity Mobile | Included in broader telecom lists |
| Sprint | Wireless | Original big four member; now part of T-Mobile |
The telecom market changes often through mergers and spectrum sales. Check each company’s latest announcements for current details.
How the Big Four Has Changed
The group looks different today than it did a decade ago.
T-Mobile and Sprint merge
The 2020 merger reduced the number of national wireless carriers from four to three.
A planned fourth carrier
DISH, later EchoStar, took over Boost Mobile and began building a network, then agreed in 2025 to sell key spectrum and rely on AT&T’s network.
Cable companies add wireless
Comcast and Charter sell mobile service through Xfinity Mobile and Spectrum Mobile, which run largely on Verizon’s network.
Fiber expansion
AT&T, Verizon and others continue to expand fiber internet, competing more directly with cable providers.
The Big Four Carriers in San Jose
All of the major carriers serve businesses across San Jose.
Phone and fiber
AT&T
The established local phone company in much of California, with fiber, wireless and business services in San Jose.
Wireless and fiber
Verizon
Wireless coverage across the city and business connectivity services.
Wireless and home internet
T-Mobile
Wireless service and fixed wireless internet in many San Jose neighborhoods.
Cable and broadband
Comcast Xfinity
Cable internet and business services across much of the city.
Which of These Carriers Is the Largest
The big four aren’t the same size, and the answer to which one is largest depends on whether you measure customers, revenue or market value. Our guide Who Is the Biggest Telecommunications Company compares them by each measure, along with the largest carriers outside the U.S.
The Big Four Telecom Companies Today
The original big four were AT&T, Verizon, T-Mobile and Sprint. Since the 2020 merger, AT&T, Verizon and T-Mobile remain the three national wireless carriers, and Comcast is often named as the fourth when broadband providers are included.
Whichever carrier you choose, its service ends where it enters your building. From there, it connects to your network in a dedicated space. Our guide What Is a Telecommunications Room explains what that space is and what goes inside it.
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