Exhibit (21) AT&T Form 10-K List of Subsidiaries of American Telephone and Telegraph Company Jurisdiction of Incorporation AT&T Capital Holdings, Inc. ............................ Delaware AT&T Communications, Inc. .............................. Delaware AT&T Communications of California, Inc. ................ California AT&T Communications of Delaware, Inc. .................. Delaware AT&T Communications of Illinois, Inc. .................. Illinois AT&T Communications of Indiana, Inc. ................... Indiana AT&T Communications of Maryland, Inc. .................. Maryland AT&T Communications of Michigan, Inc. .................. Michigan AT&T Communications of the Midwest, Inc. ............... Iowa AT&T Communications of the Mountain States, Inc. ....... Colorado AT&T Communications of Nevada, Inc. .................... Nevada AT&T Communications of New England, Inc. ............... New York AT&T Communications of New Hampshire, Inc. ............. New Hampshire AT&T Communications of New Jersey, Inc. ................ New Jersey AT&T Communications of New York, Inc. .................. New York AT&T Communications of Ohio, Inc. ...................... Ohio AT&T Communications of the Pacific Northwest, Inc. ..... Washington AT&T Communications of Pennsylvania, Inc. .............. Pennsylvania AT&T Communications of the South Central States, Inc. .. Delaware AT&T Communications of the Southern States, Inc. ....... New York AT&T Communications of the Southwest, Inc. ............. Delaware AT&T Communications of Virginia, Inc. .................. Virginia AT&T Communications of Washington, D.C. Inc. ........... New York AT&T Communications of West Virginia, Inc. ............. West Virginia AT&T Communications of Wisconsin, Inc. ................. Wisconsin AT&T Credit Holdings, Inc. ............................. Delaware AT&T Global Information Solutions Company .............. Maryland AT&T International Inc. ................................ Delaware AT&T Microelectronica de Espana S.A. ................... Spain AT&T Nassau Metals Corporation ......................... New York AT&T Network Systems International B.V. ................ Netherlands AT&T Paradyne Corporation .............................. Delaware AT&T of Puerto Rico, Inc. .............................. New York AT&T Resource Management Corporation ................... New York AT&T Universal Card Services Corp. ..................... Delaware AT&T of the Virgin Islands, Inc. ....................... Delaware Actuarial Sciences Associates, Inc. .................... Delaware American Transtech Inc. ................................ Delaware Istel Group, Ltd. ...................................... United Kingdom Teradata Corporation ................................... Delaware