It is home to the University of Texas at Dallas and the Telecom Corridor, with a high concentration of telecommunications companies. More than 5,000 businesses have operations within Richardson’s 28 square miles (73 km²), including many of the world’s largest telecommunications and networking companies, such as AT&T, Verizon, Cisco Systems, Samsung, ZTE, MetroPCS, Texas Instruments, Qorvo, and Fujitsu. Richardson’s largest employment base is provided by the insurance industry, with Blue Cross and Blue Shield of Texas’s headquarters, a regional hub for GEICO, regional offices for United Healthcare, and one of State Farm Insurance’s three national regional hubs located in the community.