SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

          ------------------------------------------------------------


                                  Schedule TO/A

                      Tender Offer Statement under Section
           14(d)(1) or 13(e)(1) of the Securities Exchange Act of 1934


                                (Amendment No. 3)


                             GRC International, Inc.
          ------------------------------------------------------------
                            (Name of Subject Company)


                                 LMN Corporation
                                   AT&T Corp.
          ------------------------------------------------------------
                        (Name of Filing Person - Offeror)


                     Common Stock, Par Value $0.10 Per Share
          ------------------------------------------------------------
                         (Title of Class of Securities)


                                   361922 10 7
          ------------------------------------------------------------
                      (CUSIP Number of Class of Securities)


                             Marilyn J. Wasser, Esq.
                          Vice President and Secretary
                                   AT&T Corp.
                            32 Avenue of the Americas
                             New York, NY 10013-2412
                            Telephone: (212) 387-5400
          ------------------------------------------------------------
            (Name, Address and Telephone Number of Person Authorized
            to Receive Notices and Communications on Behalf of Filing
                                    Persons)


                                    Copy to:
                            Steven A. Rosenblum, Esq.
                         Wachtell, Lipton, Rosen & Katz
                               51 West 52nd Street
                            New York, New York 10019
                            Telephone: (212) 403-1000





                            CALCULATION OF FILING FEE
     ---------------------------------------------------------------------


     =====================================================================
       TRANSACTION VALUATION*                     AMOUNT OF FILING FEE
     ---------------------------------------------------------------------
            $205,921,425                               $41,184.29
     =====================================================================


* Estimated for purposes of calculating the amount of filing fee only. The
amount assumes the purchase of 13,728,095 shares of common stock, par value $.10
per share (the "Shares"), at a price per Share of $15.00 in cash. Such number of
Shares represents the sum of (i) all of the Shares outstanding as of January 31,
2000, (ii) all Shares issuable upon exercise of outstanding warrants to purchase
Shares and (iii) all Shares issuable upon exercise of outstanding options to
purchase Shares that could be exercised on or prior to the expiration of the
tender offer described in this Tender Offer Statement on Schedule TO.

[X] Check box if any part of the fee is offset as provided by Rule 0-11(a)(2)
and identify the filing with which the offsetting fee was previously paid.
Identify the previous filing by registration statement number, or the Form or
Schedule and the date of its filing.

Amount Previously Paid: $41,184.29
Form or Registration No.:  Schedule TO, Amendment No. 1 to Schedule TO
Filing Party:  AT&T Corp.
Date Filed:  February 22, 2000 (Schedule TO), March 3, 2000 (Amendment No. 1)

[ ] Check the box if the filing relates solely to preliminary communications
made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the
statement relates:

[X] third-party tender offer subject to Rule 14d-1.
[ ] issuer tender offer subject to Rule 13e-4.
[ ] going-private transaction subject to Rule 13e-3.
[X] amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer: [ ]







                                Page 1 of 4 Pages





            This Amendment No. 3 (this "Amendment") amends and supplements the
Tender Offer Statement on Schedule TO filed by AT&T Corp., a New York
corporation ("AT&T"), and LMN Corporation, a Delaware corporation and a wholly
owned subsidiary of AT&T ("Purchaser"), on February 22, 2000, as amended by
Amendment No. 1 filed by AT&T and Purchaser on March 3, 2000 and Amendment No. 2
filed by AT&T and Purchaser on March 13, 2000 (as amended, the "Schedule TO"),
relating to the offer (the "Offer") by Purchaser to purchase all outstanding
shares of Common Stock, par value $0.10 per share (the "Shares"), of GRC
International, Inc., a Delaware corporation ("GRC"), at a purchase price of
$15.00 per Share, net to the seller in cash, upon the terms and subject to the
conditions set forth in the Offer to Purchase (the "Offer to Purchase") and in
the related Letter of Transmittal, copies of which are attached as Exhibits
(a)(1) and (a)(2) to the Schedule TO.

            This Amendment also amends and supplements the Statement on Schedule
13D with respect to GRC filed by AT&T and Purchaser with the Securities and
Exchange Commission on February 24, 2000.

ITEMS 1 THROUGH 9 AND 11.
- ------------------------

            Items 1 through 9 and 11 of the Schedule TO are hereby amended and
supplemented with the following information:

            On March 20, 2000, AT&T issued a press release announcing the
extension of the period of time during which the Offer will remain open to 5:00
p.m., Eastern time, on Monday, March 27, 2000. The full text of AT&T's March 20,
2000 press release is attached as Exhibit (a)(11) hereto and incorporated herein
by reference.

ITEM 12.   EXHIBITS
- -------

            Item 12 of the Schedule TO is hereby amended by adding thereto the
following:

            (a)(11)   Text of Press Release issued by AT&T on March 20, 2000.







                               Page 2 of 4 Pages





                                    SIGNATURE

            After due inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Dated:  March 21, 2000

                                        LMN CORPORATION


                                        By   /s/ Mary Jane McKeever
                                           ----------------------------------
                                           Name:   Mary Jane McKeever
                                           Title:  President




                                        AT&T CORP.


                                        By   /s/ Mary Jane McKeever
                                           ----------------------------------
                                           Name:   Mary Jane McKeever
                                           Title:  Vice President









                               Page 3 of 4 Pages





                                  EXHIBIT INDEX

(a)(11)    Text of press release issued by AT&T Corp. on March 20, 2000.









                               Page 4 of 4 Pages