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                                                                    EXHIBIT 99.6

                                   AT&T CORP.

                       OFFER TO EXCHANGE 1.176 SHARES OF
                       AT&T WIRELESS GROUP TRACKING STOCK
                      FOR EACH SHARE OF AT&T COMMON STOCK
                       UP TO AN AGGREGATE OF 427,736,486
                          SHARES OF AT&T COMMON STOCK

To Our Clients:

     Enclosed for your consideration is an Offering Circular/Prospectus dated
April 18, 2001 (the "Offering Circular/Prospectus") and a form of Letter of
Transmittal (the "Letter of Transmittal" and, together with the Offering
Circular/Prospectus, the "Exchange Offer") relating to the offer by AT&T Corp.
("AT&T") to exchange 1.176 shares of AT&T Wireless Group tracking stock for each
share of AT&T common stock validly tendered up to an aggregate of 427,736,486
shares of AT&T common stock validly tendered and exchanged. These documents may
not be used by you to tender shares of AT&T common stock.

     The material is being forwarded to you as the beneficial owner of shares of
AT&T common stock carried by us in your account but not registered in your name.
A tender of such shares of AT&T common stock may only be made by us as the
registered holder and pursuant to your instructions. Therefore, holders of
shares of AT&T common stock registered in the name of a broker, dealer,
commercial bank, trust company or other nominee should contact such registered
holder promptly if they wish to tender their shares of AT&T common stock in the
Exchange Offer.

     Accordingly, we request instructions from you as to whether you wish us to
tender any or all such shares of AT&T common stock held by us for your account
pursuant to the terms and conditions set forth in the enclosed Offering
Circular/Prospectus and the related Letter of Transmittal. This is a voluntary
Exchange Offer, which means that you may tender all, some or none of your shares
of AT&T common stock in the Exchange Offer.

     Your instructions to us should be forwarded as promptly as possible in
order to permit us to tender shares of AT&T common stock in accordance with the
provisions of the Exchange Offer. The Exchange Offer will expire at 5:00 p.m.,
New York City time, on Friday, May 25, 2001, or if extended by AT&T, the latest
date and time to which extended (the "Expiration Date"). Shares of AT&T common
stock tendered pursuant to the Exchange Offer may be withdrawn, subject to the
procedures described in the Offering Circular/ Prospectus, at any time prior to
the later of (1) the Expiration Date and (2) after the expiration of 40 business
days from the commencement of the Exchange Offer if AT&T has not theretofore
accepted such shares for exchange by AT&T.

     Your attention is directed to the following:

          1. The Exchange Offer is for up to an aggregate of 427,736,486 shares
     of AT&T common stock.

          2. AT&T's obligation to accept shares of AT&T common stock validly
     tendered in the Exchange Offer is subject to certain conditions as
     specified in the Offering Circular/Prospectus including a minimum condition
     that at least 22,883,296 shares of AT&T common stock be tendered into the
     Exchange Offer.

          3. AT&T will not be responsible for any stock transfer taxes payable
     as a result of the transaction.

          4. If you own beneficially an aggregate of fewer than 100 shares as of
     April 17, 2001 of AT&T common stock and you instruct us to tender all of
     those shares on your behalf, all such shares will be accepted for exchange
     and will not be subject to proration if the Exchange Offer is
     oversubscribed. Shares of AT&T common stock held in an AT&T or AT&T
     affiliated company savings plan are not eligible for this preferential
     treatment.

     If you wish to have us tender any or all of your shares of AT&T common
stock, please so instruct us by completing, executing and returning to us the
instruction form which appears on the reverse side of this letter.
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                                  INSTRUCTIONS

     I acknowledge receipt of your letter and the enclosed material referred to
therein relating to the Exchange Offer of AT&T Corp. ("AT&T") of AT&T Wireless
Group tracking stock in exchange for AT&T common stock. I understand, accept and
agree to the terms and conditions of the Exchange Offer.

     This will instruct you to tender in the Exchange Offer the shares of AT&T
common stock indicated below (or, if no number is indicated below, all shares)
held by you for my account, pursuant to the terms of and conditions set forth in
the Offering Circular/Prospectus and the Letter of Transmittal, including the
instructions thereto.

     Box 1  [ ]  Please tender all of my shares of AT&T common stock held by you
            for my account.

     Box 2  [ ]  Please tender (number) of the shares of AT&T common stock held
            by you for my account.
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                                    ODD-LOTS

     [ ]  By checking this box, I represent that I owned beneficially and of
record an aggregate of less than 100 shares of AT&T common stock and am
tendering all such shares.
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                                   SIGNATURE

     BY SIGNING BELOW, I HEREBY CERTIFY THAT I AM ELIGIBLE TO PARTICIPATE IN
THIS EXCHANGE OFFER.

                                                            
Dated: ----------------------------------------------------    -----------------------------------------------------------

                                                               -----------------------------------------------------------
                                                                                      SIGNATURE(S)

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                                                               -----------------------------------------------------------
                                                                                PLEASE PRINT NAME(S) HERE



     UNLESS A SPECIFIC CONTRARY INSTRUCTION IS GIVEN IN THE SPACE PROVIDED, YOUR
SIGNATURE(S) HEREON SHALL CONSTITUTE AN INSTRUCTION TO US TO TENDER ALL OF YOUR
SHARES OF AT&T COMMON STOCK.

     PLEASE RETURN THIS FORM TO THE BROKERAGE FIRM MAINTAINING YOUR ACCOUNT, NOT
AT&T, GEORGESON SHAREHOLDER COMMUNICATIONS, CREDIT SUISSE FIRST BOSTON OR LEHMAN
BROTHERS.

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