Document:

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                                                                    EXHIBIT 10.1

                                                                  Execution Copy

                               VOTING AGREEMENT

          Agreement dated as of February 28, 2000 among each of the shareholders
listed on the signature pages hereto (each, a "Shareholder") of Tritel, Inc., a
Delaware corporation ("Mississippi"), Mississippi and TeleCorp PCS, Inc., a
Delaware corporation ("Virginia").

          (A)  Virginia, Mississippi and certain other parties are parties to an
Agreement and Plan of Reorganization and Contribution dated as of the date
hereof (the "Reorganization Agreement"). Capitalized terms used herein and not
otherwise defined shall have the meaning assigned such terms in the
Reorganization Agreement.

          (B)  Each of Virginia and Mississippi agreed to enter into the
Reorganization Agreement on the condition that the parties hereto enter into
this Voting Agreement.

          Accordingly, the parties hereto agree as follows:

          1.   Representations and Warranties of Each Shareholder.  Each
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Shareholder hereby represents and warrants, severally and not jointly, to
Virginia and Mississippi as follows (with respect to itself only):

          (a)  Title.  As of the date hereof, each Shareholder beneficially
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owns the amount and class of capital stock of Mississippi set forth after such
Shareholder's name on Exhibit A attached hereto (with respect to each
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Shareholder, the capital stock specified after such Shareholder's name on
Exhibit A hereto shall be referred to herein as the "Shares").

          (b)  Right to Vote.  As of the date hereof and as of the date of the
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Mississippi Stockholder Meeting, except for this Agreement or as otherwise
permitted by this Agreement, each Shareholder has full legal power, authority
and right to vote all Shares, to the extent the Shares carry rights to vote
thereon, in favor of the Mississippi Proposals without the consent or approval
of, or any other action on the part of, any other person or entity. Without
limiting the generality of the foregoing, except for this Agreement or as
otherwise permitted by this Agreement or as disclosed in Schedule 1 hereto, each
Shareholder has not entered into any voting agreement with any person or entity
with respect to any Shares, granted any person or entity any proxy (revocable or
irrevocable) or power of attorney with respect to any Shares, deposited any
Shares in a voting trust or entered into any arrangement or agreement with any
person or entity limiting or affecting its legal power, authority or right to
vote the Shares in favor of the Mississippi Proposals. From and after the date
hereof, except as otherwise permitted by this Agreement, each Shareholder will
not commit any act that could restrict or otherwise affect such legal power,
authority and right to vote all Shares, to the extent the Shares carry the right
to vote thereon, in favor of the Mississippi Proposals. Without limiting the
generality of the foregoing, except as otherwise permitted by this Agreement,
from and after the date hereof, each Shareholder will not enter into any voting
agreement with any person or entity with respect to any of the Shares, grant any
person or entity any proxy (revocable or irrevocable) or power of attorney with
respect to any of the Shares, deposit any of the Shares in a voting trust or
otherwise enter into any agreement or arrangement limiting or affecting such
Shareholder's legal power,
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authority or right to vote the Shares in favor of the approval of the
Mississippi Proposals (other than this Agreement).

          (c)  Authority.  Each Shareholder has full legal power, authority and
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right to execute and deliver, and to perform his obligations under, this
Agreement. This Agreement has been duly and validly executed and delivered by
each Shareholder and constitutes a valid and binding agreement of each
Shareholder enforceable against each Shareholder in accordance with its terms,
subject to (i) bankruptcy, insolvency, moratorium and other similar laws now or
hereafter in effect relating to or affecting creditors rights generally and (ii)
general principles of equity (regardless of whether considered in a proceeding
at law or in equity).

          (d)  Conflicting Instruments; No Transfer.  Neither the execution and
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delivery of this Agreement nor the performance by each Shareholder of his
agreements and obligations hereunder will result in any breach or violation of
or be in conflict with or constitute a default under any term of any agreement,
judgment, injunction, order, decree, law, regulation or arrangement to which
such Shareholder is a party or by which such Shareholder (or any of his assets)
is bound, except for any such breach, violation, conflict or default which,
individually or in the aggregate, would not impair or adversely affect such
Shareholder's ability to perform its obligations under this Agreement.

          2.   Restriction on Transfer.  Each Shareholder agrees that (other
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than pursuant to the Reorganization Agreement) he will not, and will not agree
to, sell, assign, dispose of, encumber, mortgage, hypothecate or otherwise
transfer (collectively, "Transfer') any Shares, including, without limitation,
tendering any of the shares in a tender offer.

          3.   Agreement to Vote of Each Shareholder.  Each Shareholder hereby
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irrevocably and unconditionally agrees to vote or to cause to be voted all
Shares, to the extent the Shares carry the right to vote thereon, at the
Mississippi Stockholders Meeting and at any other annual or special meeting of
shareholders of Mississippi where any such proposal is submitted (a) in favor of
the Mississippi Proposals and (b) against (i) approval of any proposal made in
opposition to or in competition with the transactions contemplated by the
Reorganization Agreement, (ii) any merger, consolidation, sale of assets,
business combination, share exchange, reorganization or recapitalization of
Mississippi or any of its subsidiaries, with or involving any party other than
as contemplated by the Reorganization Agreement, (iii) any liquidation or
winding up of Mississippi, (iv) any extraordinary dividend by Mississippi, (v)
any change in the capital structure of Mississippi (other than pursuant to the
Reorganization Agreement) and (vi) any other action that may reasonably be
expected to impede, interfere with, delay, postpone or attempt to discourage the
consummation of the transactions contemplated by the Reorganization Agreement or
result in a breach of any of the covenants, representations, warranties or other
obligations or agreements of Mississippi under the Reorganization Agreement
which would materially and adversely affect Virginia or Mississippi or their
respective abilities to consummate the transactions contemplated by the
Reorganization Agreement.

          4.   Granting of Proxy.  In furtherance of the terms and provisions of
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this Agreement, each Shareholder hereby grants an irrevocable proxy (subject to
Section 10(b)), coupled with an interest, to the President and Secretary of
Virginia to vote all Shares beneficially

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owned by such Shareholder in favor of the approval of the Mississippi Proposals
and against any of the matters specified in clause (b) of Section 3. Each
Shareholder hereby ratifies and approves of each and every action taken by
Virginia pursuant to the foregoing proxy. Notwithstanding the foregoing, if
requested by Virginia, each Shareholder will execute and deliver applicable
proxy material in furtherance of the provisions of Section 3.

          5.   Action in Shareholder Capacity Only.  Each Shareholder makes no
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agreement or understanding herein as director or officer of Mississippi.  Each
Shareholder signs solely in his capacity as a record holder and beneficial owner
of the Shares, and nothing herein shall limit or affect any actions taken in his
capacity as an officer or director of Mississippi.

          6.   Invalid Provisions.  If any provision of this Agreement shall be
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invalid or unenforceable under applicable law, such provision shall be
ineffective to the extent of such invalidity or unenforceability only, without
it affecting the remaining provisions of this Agreement.

          7.   Executed in Counterparts.  This Agreement may be executed in
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counterparts each of which shall be an original with the same effect as if the
signatures hereto and thereto were upon the same instrument.

          8.   Specific Performance.  The parties hereto agree that if for any
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reason any Shareholder fails to perform any of his agreements or obligations
under this Agreement irreparable harm or injury to Virginia and Mississippi
would be caused with respect to which money damages would not be an adequate
remedy.  Accordingly, each Shareholder agrees that, in seeking to enforce this
Agreement against each Shareholder, each of Virginia and Mississippi shall be
entitled, in addition to any other remedy available at law, equity or otherwise,
to specific performance and injunctive and other equitable relief.

          9.   Governing Law; Submission to Jurisdiction.  The Agreement shall
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be governed by, and construed and enforced in accordance with, the domestic laws
of the State of Delaware without giving effect to any choice of law or conflict
of law provision or rule (whether of the State of Delaware or any other
jurisdiction) that would cause the application of the laws of any jurisdiction
other than the State of Delaware. Each of the parties hereto irrevocably agrees
that any legal action or proceeding with respect to this Agreement or for
recognition and enforcement of any judgment in respect hereof brought by the
other party hereto or its successors or assigns may be brought and determined in
the courts of the State of Delaware, and each of the parties hereto hereby
irrevocably submits with regard to any such action or proceeding for itself and
in respect to its property, generally and unconditionally, to the nonexclusive
jurisdiction of the aforesaid courts. Each of the parties hereto hereby
irrevocably waives, and agrees not to assert, by way of motion, as a defense,
counterclaim or otherwise, in any action or proceeding with respect to this
Agreement, (a) any claim that it is not personally subject to the jurisdiction
of the above-named courts for any reason, (b) that it or its property is exempt
or immune from jurisdiction of any such court or from any legal process
commenced in such courts (whether through service of judgment, execution of
judgment, or otherwise), and (c) to the fullest extent permitted by the
applicable law, that (i) the suit, action or proceeding in such court is brought
in an inconvenient forum, (ii) the venue of such suit, action or proceeding

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is improper and (iii) this Agreement, or the subject matter hereof, may not be
enforced in or by such courts.

          10.  Amendments; Termination.  (a) This Agreement may not be modified,
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amended, altered or supplemented, except upon the execution and delivery of a
written agreement executed by all parties hereto.

          (b)  The provisions of this Agreement shall terminate upon the
earliest to occur of (i) the consummation of the Mergers, and (ii) the date
which is two years after the date hereof and (iii) the termination of the
Reorganization Agreement.

          (c)  For purposes of this Agreement, the term "Reorganization
Agreement" includes the Reorganization Agreement, as the same may be modified or
amended from time to time.

          11.  Additional Shares.  If, after the date hereof, any Shareholder
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acquires beneficial ownership of any additional shares of capital stock of
Mississippi (any such shares, "Additional Shares"), including, without
limitation, upon exercise of any option, warrant or right to acquire Shares of
capital stock of Mississippi or through any stock dividend or stock split, the
provisions of this Agreement applicable to the Shares shall be applicable to
such Additional Shares as if such Additional Shares had been Shares as of the
date hereof.  The provisions of the immediately preceding sentence shall be
effective with respect to Additional Shares without action by any person or
entity immediately upon the acquisition by any Shareholder of beneficial
ownership of such Additional Shares.

          12.  Successors and Assigns.  The provisions of this Agreement shall
               ----------------------
be binding upon and inure to the benefit of the parties hereto and their
respective legal successors (including, in the case of any Shareholder or any
other individual, any executors, administrators, estates, legal representatives
and heirs of such Shareholder or such individual) and permitted assigns;
provided, however, that, except as otherwise provided in this Agreement, no
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party may assign, delegate or otherwise transfer any of its rights or
obligations, under this Agreement, without the consent of Virginia and
Mississippi, in the case of any Shareholder, the Shareholders and Mississippi,
in the case of Virginia, and the Shareholders and Virginia in the case of
Mississippi. Without limiting the scope or effect of the restrictions on
Transfer set forth in Section 2 hereof, each Shareholder agrees that this
Agreement and the obligations hereunder shall attach to the Shares and shall be
binding upon any person or entity to which legal or beneficial ownership of such
Shares shall pass, whether by operation of law or otherwise.

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          IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of this 28 day of February, 2000.

                                             Tritel, Inc.

                                             By: _________________________
                                                 Name: ___________________
                                                 Title: __________________

                                             TeleCorp PCS, Inc.

                                             By: _________________________
                                                 Name: ___________________
                                                 Title: __________________

                                             E.B. Martin, Jr.

                                             By: _________________________
                                                 Name: ___________________
                                                 Title: __________________

                                             William M. Mounger, II

                                             By: _________________________
                                                 Name: ___________________
                                                 Title: __________________
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                                                                       EXHIBIT A

          Shareholder Name                   Amount and Class of Shares
          ----------------                   --------------------------

E.B. Martin Jr.                    Class A Common    2,384,544
                                   Class C Common    690,224
                                   Voting Preference 3

          Shareholder Name                   Amount and Class of Shares
          ----------------                   --------------------------

William M. Mounger, II             Class A Common    2,384,544 (directly)
                                   Class A Common    2,379,072.22 (indirectly
                                                     through a trust, Trillium
                                                     PCS, and M3, LLC)
                                   Class C Common    690,224
                                   Class D Common    148,598.04 (indirectly
                                                     through Trillium PCS and
                                                     M3, LLC)
                                   Voting Preference 3

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Note: Mounger has a controlling interest in Trillium PCS, LLC and M3, LLC.
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                                   SCHEDULE 1

     The Stockholders' Agreement, dated as of January 7, 1999, by and among
Tritel, Inc., William M. Mounger, II, E.B. Martin, Jr. and the other
stockholders named therein.<PAGE>

                                                                Exhibit 10(dd)

                                                   December 20, 1999

THIS LETTER CONSTITUTES PART OF A PROSPECTUS
COVERING SECURITIES THAT HAVE BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED

   RE:  Lockheed Martin Corporation 1995 Omnibus Performance Award Plan ("Plan")

Dear Optionee:

   Effective December 2, 1999, the Stock Option Subcommittee of the Board of
Directors of Lockheed Martin Corporation (the "Corporation") has amended the
terms of your outstanding Lockheed Martin stock options previously granted under
the referenced Plan.  The amendments provide that:

 .  If you die, the expiration date of your outstanding options will be
   unaffected and will expire at the end of their remaining term. This amends
   the duration of the exercise period for your beneficiaries from three years
   following your death to the end of your options' remaining term.

 .  If you are divested from the Corporation as defined in your outstanding Plan
   award agreements, the vesting schedule of your outstanding options will be
   unaffected by the divestiture and your outstanding options will expire on the
   fifth anniversary of the effective date of the divestiture, or the original
   expiration date, whichever occurs first. This amends the duration of the
   exercise period following divestiture from one year to five years (but in no
   case longer than the original term), and provides for continued vesting of
   your options following divestiture (previously, unvested options at the time
   of the divestiture were forfeited). The provision concerning your rights upon
   voluntary or involuntary termination (other than layoff) has also been
   amended but the amendments are technical and do not change the meaning of the
   provision.

The full text of the amendments (including non-substantive technical changes) as
implemented in the award letters previously issued to you follow:

     SPECIAL RULES AS TO EXPIRATION AND FORFEITURE

       Death - Options will expire at the end of their remaining term.

       Resignation, Lay-Off or Termination for Cause - If you resign or
     otherwise terminate, whether voluntarily or by action of the Corporation
     and in the latter case
<PAGE>

     whether with or without "cause," unvested Options will be forfeited upon
     your termination. Vested Options will expire at the end of their remaining
     term or 186 calendar days following your resignation or termination,
     whichever is shorter. If you are laid off, your options will be unaffected,
     and will vest and be exercisable until the end of their remaining term, in
     accordance with the terms of the Plan.

       Divestiture - If the Corporation divests (as defined below) all or
     substantially all of a business operation of the Corporation and such
     divestiture results in the termination of the recipient's employment with
     the Corporation or its subsidiaries and transfer of such employment to the
     other party to the divestiture, the special rules in this paragraph will
     apply.  Your service with the other party to the divestiture will be
     treated as service with the Corporation and you will continue to vest in
     your unvested options while employed by that party as though you had
     remained in the employ of the Corporation.  Following a divestiture, your
     vested options will be exercisable until the first to occur of (i) the
     fifth anniversary of the effective date of the divestiture; or (ii) the
     original expiration date ("Divestiture Expiration Date").  If you die
     following divestiture but prior to the Divestiture Expiration Date, all
     unvested options will immediately vest as of the date of death and be
     exercisable by your beneficiary until the Divestiture Expiration Date.  For
     the purposes of this provision, the term "divestiture" shall mean a
     transaction which results in the transfer of control of the business
     operation divested to any person, corporation, association, partnership,
     joint venture or other business entity of which less than 50% of the voting
     stock or other equity interests (in the case of entities other than
     corporations), is owned or controlled directly or indirectly, by the
     Corporation, one or more of the Corporation's subsidiaries or by a
     combination thereof.

   This letter is intended to notify each holder of options under the Plan that
the amendments have been fully implemented on a prospective basis as of December
2, 1999 and will apply to divestitures and deaths occurring after that date.
Except for the amendments, which serve as an extension of the exercise periods
under circumstances of divestiture or death from those previously authorized,
each option remains in full force and effect in accordance with its terms in
effect prior to the amendments.  The amendments do not apply at this time to
Section 16 Insiders.

   If you have questions regarding the amendments, please address them to ____,
or me.

                                                Very truly yours,

                                                /s/ Lillian M. Trippett

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