|[Front]


Agere Systems
|-----------------------

|(NUMBER)                                                                  | (SHARES)                                                                                                
|------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------
|                                                                         
|CLASS B COMMON STOCK
INCORPORATED UNDER THE LAWS OF
THE STATE OF DELAWARE | THIS CERTIFICATE IS TRANSFERABLEIN NEW YORK, NY
CUSIP  00845V209SEE REVERSE SIDE FOR CERTAIN DEFINITIONS

|THIS CERTIFIES THAT


IS THE OWNER OF


FULLY PAID AND NON-ASSESSABLE CLASS
B COMMON SHARES, $.01 PAR VALUE, OF


Agere Systems Inc.


transferable on the records
of the corporation in person or by duly authorized attorney upon surrender of
this certificate properly endorsed. This certificate is not valid unless
countersigned by a Transfer Agent and registered by a Registrar.


WITNESS
the seal of said corporation and the signatures of its duly authorized officers.


DATED:
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|            |  | ( | Agere Systems Inc. | ) |  |            
|----------- |  | - | ------------------ | - |  | -----------
|            |  | ( | Corporate          | ) |  |            
|(SIGNATURE) |  | ( | SEAL               | ) |  | (SIGNATURE)
|            |  | ( | 2000               | ) |  |            
|TREASURER   |  | ( | DELAWARE           | ) |  | PRESIDENT  
|            |  |   |                    |   |  |            

|COUNTERSIGNED
      AND REGISTERED                                                   
|-------------------------------------------------------------------------------------
|The Bank of New York
                  Transfer Agent
                  and Registrar
|                                                                                     
|By
      (Signature)                                                                 
|Authorized Signature                                                                 

|2



[Reverse]



AGERE SYSTEMS INC.


THE
CORPORATION WILL FURNISH WITHOUT CHARGE TO EACH STOCKHOLDER WHO SO REQUESTS A
STATEMENT OF THE POWERS, DESIGNATIONS, PREFERENCES AND RELATIVE, PARTICIPATING,
OPTIONAL OR OTHER SPECIAL RIGHTS OF EACH CLASS OF STOCK OR SERIES THEREOF OF THE
CORPORATION AND THE QUALIFICATIONS, LIMITATIONS OR RESTRICTIONS OF SUCH
PREFERENCES AND/OR RIGHTS. SUCH REQUEST MAY BE MADE TO THE TRANSFER AGENT.


The
following abbreviations, when used in the inscription on the face of this
certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|        |  |   |  |                                                                          |  |                   |  | Custodian | 
|------- |  | - |  | ------------------------------------------------------------------------ |  | ----------------- |  | --------- | 
|TEN COM |  |  |  | as tenants in common                                                     |  | UNIF GIFT MIN ACT |  |           | 
|        |  |   |  |                                                                          |  |                   |  |           | 
|        |  |   |  |                                                                          |  |                   |  | (Cust)    | 
|        |  |   |  | under Uniform Gifts to Minors Act                                        |  |                   |  |           | 
|        |  |   |  |                                                                          |  |                   |  |           | 
|TEN ENT |  |  |  | as tenants by the entireties                                             |  |                   |  | (State)   | 
|       
|JT TEN  |  |  |  | as joint tenants with right of survivorship and not as tenants in common

|Additional
abbreviations may also be used though not in the above list.



For value received, __________________ hereby sell, assign and transfer unto



PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFICATION NUMBER OF ASSIGNEE
   [            
               
               
            ]
   [            
               
               
            ]
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|                                                                                 
|---------------------------------------------------------------------------------
|PLEASE PRINT
OR TYPEWRITE NAME AND ADDRESS INCLUDING POSTAL ZIP CODE, OF ASSIGNEE

|_________________________________________________________________________Shares
of the Class B Common Stock represented by the within Certificate and do hereby
irrevocably constitute and appoint _____________________________________________________________________________________
___________________________________ Attorney
to transfer the said stock on the books of the within-named Corporation with
full power of substitution in the premises.



Dated: _____________
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| |  | By

THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS,
STOCKBROKERS, SAVINGS AND LOANS ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP
IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM) PURSUANT TO S.E.C. RULE 17Ad-15.
| |  | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|This
certificate also evidences and entitles the holder hereof to certain Class B
Rights as set forth in a Rights Agreement between Agere Systems Inc. and The
Bank of New York, dated as of March 26, 2001, as amended from time to time (the
Rights Agreement), the terms of which are hereby incorporated herein
by reference and a copy of which is on file at the principal executive offices
of Agere Systems Inc. Under certain circumstances, as set forth in the Rights
Agreement, such Class B Rights will be evidenced by separate certificates and
will no longer be evidenced by this certificate. Agere Systems Inc. will mail to
the holder of this certificate a copy of the Rights Agreement without charge
after receipt of a written request therefor. Under certain circumstances, as set
forth in the Rights Agreement, Class B Rights owned by or transferred to any
Person who is or becomes an Acquiring Person (as defined in the Rights
Agreement) and certain transferees thereof will become null and void and will no
longer be transferable.


NOTICE: The signature to
this assignment must correspond with the name as written upon the face of the
Certificate in every particular, without alteration or enlargement or any change
whatever.
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------