Exhibit 21 SUBSIDIARIES OF SOUTHWESTERN BELL CORPORATION AS OF JANUARY 1, 1994 State of Conducts Name Incorporation Business Under Southwestern Bell Missouri Same Telephone Company Southwestern Bell Dually Same Mobile Systems, Inc. incorporated in Delaware and Virginia SBC International, Inc. Delaware Same Southwestern Bell Missouri Same Yellow Pages, Inc. Associated Directory Delaware Same Services, Inc. Southwestern Bell Delaware Same Telecommunications, Inc. Southwestern Bell Missouri Same Printing Company Southwestern Bell Delaware Same Enterprises, Inc.