AT&T Inc.

The wireless business contributes about 70% of AT&T's revenue. The company is the third-largest US wireless carrier, connecting 75 million postpaid and 17 million prepaid phone customers. Fixed-line enterprise services, which account for about 13% of revenue, include internet access, private networking, security, voice, and wholesale network capacity. Residential services, about 12% of revenue, primarily consist of in-home broadband internet access, serving 16 million customers across a network footprint that reaches more than 60 million homes. AT&T also has a sizable presence in Mexico, with 23 million wireless customers, but this business only accounts for 3% of revenue.