XO Communications is one of the leading providers of communications services for businesses and communications services providers, including Fortune 500 and cable companies, carriers, content providers and mobile operators. It offers data, Internet, Internet protocol virtual private network, Ethernet, digital subscriber and private line services. The company also offers voice over Internet protocol, network security and maintenance services. Additionally, XO Communications offers Web hosting and managed services. Headquartered in Herndon, Va., it maintains locations throughout the United States, including one in Phoenix. The company has partnerships with Cisco Systems, ConnectHere Communications, Telarus, Data-Tel Communications, Telco IQ, Gryphone Telecom, Telecom Brokerage, KeaneTel, World Telecom Group, Intelisys, X4 Communications and PlanetOne Communications. XO Communications employs a staff of more than 4,000 people. It is a part of XO Holdings.