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                                                                     EXHIBIT 3.1


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                          CERTIFICATE OF INCORPORATION

                                       OF

                             INET TECHNOLOGIES, INC.

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                                   ARTICLE I.

       The name of this Corporation shall be Inet Technologies, Inc.


                                   ARTICLE II.

       The address of the registered office of the Corporation in the State of
Delaware is 1209 Orange Street, City of Wilmington, County of New Castle, State
of Delaware. The name of the registered agent at that address is The Corporation
Trust Company.

                                  ARTICLE III.

       The purpose of the Corporation is to engage in any lawful act or activity
for which corporations may be organized under the Delaware General Corporation
Law.

                                   ARTICLE IV.

       The name and mailing address of the incorporator of the Corporation is:

                              Mark A. Weinzierl
                              1255 West 15th Street
                              Plano, TX 75075-7270

                                   ARTICLE V.

       A. Authorized Shares. The aggregate number of shares that the Corporation
shall have authority to issue is 200,000,000, (i) 175,000,000 shares of which
shall be Common Stock, par value $0.001 per share, and 25,000,000 of which shall
be Preferred Stock, par value $0.001 per share.

       B. Common Stock. Each share of Common Stock shall have one vote on each
matter submitted to a vote of the stockholders of the Corporation. Subject to
the provisions of applicable law and the rights of the holders of the
outstanding shares of Preferred Stock, if any, the holders of shares of Common
Stock shall be entitled to receive, when and as declared by the Board of
Directors of the Corporation, out of the assets of the Corporation legally
available therefor, dividends or other distributions, whether payable in cash,
property or securities of the 


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Corporation. The holders of shares of Common Stock shall be entitled to receive,
in proportion to the number of shares of Common Stock held, the net assets of
the Corporation upon dissolution after any preferential amounts required to be
paid or distributed to holders of outstanding shares of Preferred Stock, if any,
are so paid or distributed.

       C. Preferred Stock. The Preferred Stock may be issued from time to time
by the Board of Directors as shares of one or more series. The description of
shares of each additional series of Preferred Stock, including any designations,
preferences, conversion and other rights, voting powers, restrictions,
limitations as to dividends, qualifications, and terms and conditions of
redemption shall be as set forth in resolutions adopted by the Board of
Directors.

       The Board of Directors is expressly authorized, at any time, by adopting
resolutions providing for the issuance of, or providing for a change in the
number of, shares of any particular series of Preferred Stock and, if and to the
extent from time to time required by law, by filing certificates of amendment or
designation which are effective without stockholder action, to increase or
decrease the number of shares included in each series of Preferred Stock, but
not below the number of shares then issued, and to set in any one or more
respects the designations, preferences, conversion or other rights, voting
powers, restrictions, limitations as to dividends, qualifications, or terms and
conditions of redemption relating to the shares of each such series. The
authority of the Board of Directors with respect to each series of Preferred
Stock shall include, but not be limited to, setting or changing the following:

       a.     the dividend rate, if any, on shares of such series, the times of
              payment and the date from which dividends shall be accumulated, if
              dividends are to be cumulative;

       b.     whether the shares of such series shall be redeemable and, if so,
              the redemption price and the terms and conditions of such
              redemption;

       c.     the obligation, if any, of the Corporation to redeem shares of
              such series pursuant to a sinking fund;

       d.     whether shares of such series shall be convertible into, or
              exchangeable for, shares of stock of any other class of classes
              and, if so, the terms and conditions of such conversion or
              exchange, including the price or prices or the rate or rates of
              conversion or exchange and the terms of adjustment, if any;

       e.     whether the shares of such series shall have voting rights, in
              addition to the voting rights provided by law, and, if so, the
              extent of such voting rights;

       f.     the rights of the shares of such series in the event of voluntary
              or involuntary liquidation, dissolution or winding-up of the
              Corporation; and


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       g.     any other relative rights, powers, preferences, qualifications,
              limitations or restrictions thereof relating to such series.

                                   ARTICLE VI.

       A director of the Corporation shall not be personally liable to the
Corporation or its stockholders for monetary damages for breach of fiduciary
duty as a director, except for liability (i) for any breach of the director's
duty of loyalty to the Corporation or its stockholders, (ii) for acts or
omissions not in good faith or which involve intentional misconduct or a knowing
violation of law, (iii) under Section 174 of the Delaware General Corporation
Law, or (iv) for any transaction from which the director derived any improper
personal benefit. If the Delaware General Corporation Law is amended after
approval by the stockholders of this Article to authorize corporate action
further eliminating or limiting the personal liability of directors, then the
liability of a director of the Corporation shall be eliminated or limited to the
fullest extent permitted by the Delaware General Corporation Law as so amended.

                                  ARTICLE VII.

       The management of the business and the conduct of the affairs of the
Corporation shall be vested in its Board of Directors. The number of directors
which shall constitute the whole Board of Directors shall be fixed by, or in the
manner provided in, the Bylaws of the Corporation.

                                  ARTICLE VIII.

       Meetings of stockholders may be held within or without the State of
Delaware, as the Bylaws may provide. The books of the Corporation may be kept
(subject to any provision contained in the statutes) outside the State of
Delaware at such place or places as may be designated from time to time by the
Board of Directors or in the Bylaws of the Corporation.

                                   ARTICLE IX.

       Election of directors at an annual or special meeting of stockholders
need not be by written ballot unless the Bylaws of the Corporation shall so
provide.

                                   ARTICLE X.

       A. At each annual meeting of stockholders, directors of the Corporation
shall be elected to hold office until the expiration of the term for which they
are elected, and until their successors have been duly elected and qualified;
except that if any such election shall not be so held, such election shall take
place at a stockholders' meeting called and held in accordance with the Delaware
General Corporation Law. At the first annual meeting of stockholders (the "First
Public Company Annual Meeting") following the closing of the initial public
offering of the Corporation's capital stock pursuant to an effective
registration statement filed under the Securities Act of 1933, as amended (the
"Initial Public Offering"), the directors 


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of the Corporation shall be divided into three classes as nearly equal in size
as is practicable, hereby designated as Class I, Class II and Class III. The
term of office of the initial Class I directors shall expire at the next
succeeding annual meeting of stockholders, the term of office of the initial
Class II directors shall expire at the second succeeding annual meeting of
stockholders and the term of office of the initial Class III directors shall
expire at the third succeeding annual meeting of stockholders. For the purposes
hereof, the initial Class I, Class II and Class III directors shall be those
directors designated and elected at the First Public Company Annual Meeting. At
each annual meeting after the First Public Company Annual Meeting, directors to
replace those of a Class whose terms expire at such annual meeting shall be
elected to hold office until the third succeeding annual meeting and until their
respective successors shall have been duly elected and qualified. If the number
of directors is hereafter changed, any newly created directorships or decrease
in directorships shall be so apportioned among the classes as to make all
classes as nearly equal in number as is practicable.

       B. Vacancies occurring on the Board of Directors for any reason may be
filled by vote of a majority of the remaining members of the Board of Directors,
although less than a quorum, at a meeting of the Board of Directors. A person so
elected by the Board of Directors to fill a vacancy shall hold office until the
next succeeding annual meeting of stockholders of the Corporation and until his
or her successor shall have been duly elected and qualified.

                                   ARTICLE XI.

       In furtherance and not in limitation of the powers conferred by statute,
the Board of Directors is expressly authorized to make, alter, amend or repeal
the Bylaws of the Corporation.

                                  ARTICLE XII.

       Effective upon the closing of the Initial Public Offering, stockholders
of the Corporation may not take action by written consent in lieu of a meeting
but must take any actions at a duly called annual or special meeting.

                                  ARTICLE XIII.

       Notwithstanding any other provisions of this Certificate of Incorporation
or any provision of law which might otherwise permit a lesser vote or no vote,
but in addition to any affirmative vote of the holders of the capital stock
required by law or this Certificate of Incorporation, the affirmative vote of
the holders of at least two-thirds (2/3) of the combined voting power of all of
the then-outstanding shares of the Corporation entitled to vote shall be
required to alter, amend or repeal Articles X, XII or XIII or any provisions
thereof.


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                                  ARTICLE XIV.

       The Corporation reserves the right to amend, alter, change or repeal any
provision contained in this Certificate of Incorporation, in the manner now or
hereafter prescribed by statute, and all rights conferred on stockholders herein
are granted subject to this reservation.


                            [Signature page follows]


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       THE UNDERSIGNED, being the incorporator named herein, for the purpose of
forming a corporation to do business both within and without the State of
Delaware and pursuant to the General Corporation Law of the State of Delaware,
does make and file this Certificate of Incorporation of Inet Technologies, Inc.,
hereby declaring and certifying that the facts herein stated are true, and
accordingly has hereunto set his hand this ___ day of ______, 1998.



                                          --------------------------------------
                                          Mark A. Weinzierl
                                          Executive Vice President and Secretary












                [SIGNATURE PAGE TO CERTIFICATE OF INCORPORATION]