# EXHIBIT 21

# Tellabs Inc. and Subsidiaries
Subsidiaries of the Registrant
as of December 31, 2003

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|---------------------------------------------- | 
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|                                              
|Tellabs San Jose, Inc.                         | 
|Tellabs Reston, Inc.                           | 
|White Oak Merger Corp.                         | 
|NetCore Systems, Inc.                          | 
|Salix Technologies, Inc.                       | 
|Future Networks, Inc.                          | 
|Tellabs Mexico, Inc.                           | 
|Tellabs de Mexico, S.A. de C.V                 | 
|Tellabs TG, Inc.                               | 
|Tellabs Transport Group, Inc.                  | 
|Tellabs Operations, Inc.                       | 
|Telecommuncations Laboratories, Inc.           | 
|Telecon Acquisition Corp.                      | 
|Tellabs Export, Inc.                           | 
|Tellabs Japan, Inc.                            | 
|Tellabs Manufacturing, Inc.                    | 
|Tellabs International, Inc.                    | 
|Tellabs Communications Canada Ltd.             | 
|Tellabs do Brazil, Ltda                        | 
|Tellabs H.K. Ltd.                              | 
|Tellabs Pty. Ltd.                              | 
|Tellabs International de Mexico                | 
|Tellabs Asia Pacific Private Limited           | 
|Tellabs (Thailand) Co., Ltd.                   | 
|Tellabs Korea, Inc.                            | 
|Tellabs India Private Limited                  | 
|Tellabs Communications International Ltd.      | 
|Tellabs de Venezuela, S.A                      | 
|Tellabs Communications (Malaysia) Sdn Bhd      | 
|Tellabs Malaysia Sdn Bhd (49% joint venture)   | 
|Tellabs Holdings, B.V                          | 
|Tellabs Enterprises B.V                        | 
|Tellabs Oy                                     | 
|Kiinteisto Oy Mestarinkaare                    | 
|Kiinteisto Oy Sinimaentie 6                    | 
|Tellabs Denmark A/S                            | 
|Tellabs Communications (India) Private Limited | 
|FIBCOM India Ltd (40% Joint Venture)           | 
|Tellabs Holdings, Ltd.                         | 
|Tellabs (Ireland) Ltd                          | 
|Tellabs Ltd.                                   | 
|Tellabs Research Ltd.                          | 
|Tellabs Communications Ireland Limited         | 
|Tellabs Communications Technologies            | 
|Tellabs EMEA Holdings, Ltd.                    | 
|Tellabs AB                                     | 
|Tellabs (S.A.) (Proprietary) Limited           | 
|Tellabs SAS                                    | 
|Tellabs Italia S.r.l                           | 
|Tellabs Netherlands B.V                        | 
|Tellabs Poland Sp. z o.o                       | 
|Tellabs Southern Europe S.A                    | 
|Tellabs Gmbh                                   | 
|Tellabs Austria Vertriebs GmbH                 | 
|Tellabs Norway A/S                             | 
|Tellabs U.K. Ltd.                              | 
|Tellabs Communications UK Limited              | 
|E. Coherent Communications Systems Ltd.        |