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AT&T is the successor to Alexander Graham Bell's phone company. The company grew so large that the federal government had to regulate it. In 1913, the Department of Justice brought an antitrust suit against AT&T that resulted in the Kingsbury Commitment. It forced AT&T to divest itself of Western Union and allow independent carriers to use the long-distance network it had established. In 1956, the Justice Department limited AT&T to providing only regulated services to customers and, in 1968, ruled that customers could attach non-AT&T equipment to the public telephone network. The 1969 MCI Decision allowed MCI and other carriers to compete with AT&T for long-distance communications.

From 1982 to 1984, the Justice Department finalized its antitrust suit by forcing AT&T to break up and re-form into seven regional holding companies called RBOCs (regional Bell operating companies), or "Baby Bells." A manufacturing, research, and long-distance operation called AT&T Corporation was allowed to continue operation. Refer to "Telecommunications Regulation" for more information about the breakup.

More recently, AT&T has been getting back into local service markets. It now provides service in almost 100 major cities. AT&T acquired a number of companies, including TCG (Teleport Communications Group) and TCI (Tele-Communication, Inc.). AT&T is also in a joint venture with British Telecom and acquired IBM's global data network in December of 1998. The TCG acquisition gives AT&T access to a number of local service markets and the 38-GHz wireless spectrum that TCG owned. The wireless service gives subscribers access to AT&T's wireless local access service. The TCI acquisition gives AT&T access to broadband hybrid fiber-coax networks that reach almost one-third of U.S. households. TCI controlled @Home Network, which gives AT&T further access to services that support Internet users.

AT&T is also involved with the support of Internet traffic and voice/data networking. It is upgrading much of its network with Cisco gigabit routers and switches from Nortel and Lucent to handle packet-based voice traffic.

In January of 1999, AT&T announced INC (Integrated Network Connection), a multiservice access solution for small and large businesses that is similar to Sprint's ION (Integrated On -demand Network). In its initial offering, INC supports up to 40 voice calls simultaneously with 512 Kbits/sec of data and Internet Protocol (IP) traffic using an AT&T-owned ATM multiplexer located on the customer's premises. The multiplexer will automatically react to users' dynamic demands for different types of network traffic and allocate bandwidth accordingly, whether that be voice, frame relay, IP traffic, or video communications.

AT&T also provides extensive support for VPNs (virtual private networks). Its Enterprise Class Virtual Private Network (VPN) services combine frame relay, due to its reliability, and IP, due to its ubiquity and flexibility. The services implement some interesting features such as support for MPLS (Multiprotocol Label Switching), QoS (quality of service), and IPSec (IP Security ) encryption techniques.

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