<PAGE>

                                                                     Exhibit 3.1

                                                                  As of 11/10/98
                                AMENDED BY-LAWS
                                       OF
                                IFX CORPORATION

                                   ARTICLE I
                                   ---------
                                    OFFICES
                                    -------

     SECTION 1.  REGISTERED OFFICE.  The registered office shall be established
and maintained at 1013 Centre Road, City of Wilmington, in the County of New
Castle in the State of Delaware.

     SECTION 2.  OTHER OFFICES.  The corporation may have other offices, either
within or without the State of Delaware, at such place or places as the Board of
Directors may from time to time appoint or the business of the corporation may
require.

                                   ARTICLE II
                                   ----------
                            MEETING OF STOCKHOLDERS
                            -----------------------

     SECTION 1.  ANNUAL MEETINGS.  Annual meetings of stockholders for the
election of directors and for such other business as may be stated in the notice
of the meeting, shall be held at such place, either within or without the State
of Delaware, and at such time and date as the Board of Directors, by resolution,
shall determine and as set forth in the notice of the meeting.  In the event the
Board of Directors fails to so determine the time, date and place of meeting,
the annual meeting of stockholders shall be held at the main business office of
the corporation in Delaware on the last Friday of October of each year.

     If the date of the annual meeting shall fall upon a legal holiday, the
meeting shall be held on the next succeeding business day.  At each annual
meeting, the stockholders entitled to vote shall elect a Board of Directors and
may transact such other corporate business as shall be stated in the notice of
the meeting.

     SECTION 2.  OTHER MEETINGS.  Meetings of stockholders for any purpose other
than the election of directors may be held at such time and place, within or
without the State of Delaware, as shall be stated in the notice of the meeting.

     SECTION 3.  VOTING.  Each stockholder shall be entitled to vote in
accordance with the terms and provisions of the Certificate of Incorporation and
these By-Laws, in person or by proxy, but no proxy shall be voted after three
years from its date unless such proxy provides for a longer period.  All
elections for directors shall be decided by plurality vote; an other questions
shall be decided by majority vote except as otherwise provided by the
Certificate of Incorporation or the laws of the State of Delaware.

     SECTION 4.  PROXIES.  A stockholder may execute a writing authorizing
another person or persons to act for him as proxy.  Execution may be
accomplished by the stockholder or his authorized officer, director, employee or
agent signing such writing or causing his or her signature to be affixed to such
writing by any reasonable means including, but not limited to, by facsimile
signature.
<PAGE>

     A duly executed proxy shall be irrevocable if it states that it is
irrevocable and if, and only as long as, it is coupled with an interest
sufficient in law to support an irrevocable power.  A proxy may be made
irrevocable regardless of whether the interest with which it is coupled is an
interest in the stock itself or an interest in the corporation generally.

     SECTION 5.  FIXING OF RECORD DATE.  For the purpose of determining the
shareholders entitled to notice of or to vote at any meeting of shareholders or
any adjournment thereof, or to express consent to corporate action in writing
without a meeting, or to receive payment of any dividend, or other distribution
or allotment of any rights, or to exercise any rights in respect of any change,
conversion or exchange of shares or for the purpose of any other lawful action,
the board of directors of the corporation may fix in advance a record date which
shall not be more than sixty days and not less than ten days, or in the case of
a merger or consolidation, not less than twenty days, before the date of such
meeting.  If no record date is fixed, the record date for the determination of
shareholders entitled to notice of or to vote at a meeting of shareholders shall
be at the close of the business day on the day next preceding the day on which
notice is given and the record date for the determination of shareholders for
any other purpose shall be the date on which the board of directors adopts the
resolution relating thereto.  A determination of shareholders of record entitled
to notice of or to vote at a meeting of shareholders shall apply to any
adjournment of the meeting.

     SECTION 6.  QUORUM.  In all matters, except as otherwise required by law,
by the Certificate of Incorporation or by these By-Laws, the presence, in person
or by proxy, of stockholders holding a majority of the stock of the corporation
entitled to vote shall constitute a quorum at all meetings of the stockholders.
In case a quorum shall not be present at any meeting, a majority in interest of
the stockholders entitled to vote thereat shall have power to adjourn the
meeting from time to time, without notice other than announcement at the
meeting, until the requisite amount of stock entitled to vote shall be present.
At any such adjourned meeting at which the requisite amount of stock entitled to
vote shall be represented, any business may be transacted which might have been
transacted at the meeting as originally noticed; but only those stockholders
entitled to vote at the meeting as originally noticed shall be entitled to vote
at any adjournment or adjournments thereof

     SECTION 7.  SPECIAL MEETINGS.  Special meetings of the stockholders, for
any purpose, unless otherwise prescribed by statute or by the Certificate of
Incorporation, may be called by Board of Directors.

     SECTION 8.  NOTICE OF MEETINGS.  Written notice, stating the place, date
and time of the meeting, and the general nature of the business to be
considered, shall be given to each stockholder entitled to vote thereat at his
address as it appears on the records of the corporation, not less than ten nor
more than sixty days before the date of the meeting, either personally or by
mail, by or at the direction of the president, or the secretary, or the officer
or persons calling the meeting, to each shareholder of record entitled to vote
at such meeting.  If mailed, such notice shall be deemed to be delivered when
deposited in the United States mail, addressed to the shareholder at his address
as it appears on the records of the corporation, with the postage thereon
prepaid.

                                      -2-
<PAGE>

     Whenever any notice whatever is required to be given under the provisions
of any law, or under the provisions of the Certificate of Incorporation of the
corporation or these By-Laws, a waiver thereof in writing signed by the person
or persons entitled to said notice, whether before or after the time stated
therein, shall be deemed proper notice.

     SECTION 9.  ACTION WITHOUT MEETING.  Any action that is ordinarily taken at
any annual or special meeting of stockholders may be taken without a meeting,
without prior notice, and without a vote, if a consent or consents in writing,
setting forth the action so taken, shall be signed by the holders of outstanding
stock having not less than the minimum number of votes that would be necessary
to authorize or take such action at a meeting at which all shares entitled to
vote thereon were present and voted, and shall be delivered to the Corporation
by delivery to its registered office, its principal place of business or an
officer or agent of the Corporation having custody of the book in which
proceedings of meetings of stockholders are recorded.  Delivery made to the
Corporation's registered office shall be by hand or by certified or regular
mail, return receipt requested.

                                  ARTICLE III
                                  -----------
                                   DIRECTORS
                                   ---------

     SECTION 1.  NUMBER. The minimum number of directors which shall constitute
the entire Board of Directors shall be one.  The number of directors to
constitute the Board of Directors shall be fixed from time to time by resolution
of the Board of Directors.  The directors shall be elected at the annual or
special meeting of the stockholders (except as otherwise provided in Section 8
of this Article III), and each director elected shall hold office until his or
her successor is elected and qualified, or until his or her earlier death,
resignation or removal.  Directors need not be stockholders.

     SECTION 2.  REGULAR MEETINGS.  Regular meetings of the Board of Directors
shall be held at such place or places, on such date or dates, and at such time
or times as shall have been established by the board of directors and publicized
among all directors.  A notice of such regular meeting shall not be required.

     SECTION 3.  SPECIAL MEETINGS.  Special meetings of the Board of Directors
may be called by the President or any two directors and shall be held at such
place, on such date and at such time as they or he shall fix Notice of the
place, date and time of each such special meeting shall be given each director
by whom it is not waived, by mailing written notice not less than two days
before the meeting or, by telegraphing the same not less than 18 hours before
the meeting, to each director at his business address.  If mailed, such notice
shall be deemed to be delivered, when deposited in the United States mail so
addressed, with postage thereon prepaid.  The attendance of a director at any
meeting shall constitute a waiver of notice of such meeting, except where a
director attends a meeting for the express purpose of objecting to the
transaction of any business because the meeting is not lawfully called or
convened.  Neither the business to be transacted at, nor the purpose of any
regular or special meeting of the Board of Directors need be specified in any
written waiver of notice.

     SECTION 4.  QUORUM.  At any meeting of the Board of Directors, one-half of
the numbers of directors then in office, but not less than two, shall constitute
a quorum for all

                                      -3-
<PAGE>

purposes. If a quorum shall fail to attend any meeting, a majority of those
present may adjourn the meeting to another place, date or time without further
notice or waiver thereof.

     SECTION 5.  PARTICIPATION AND MEETINGS BY CONFERENCE TELEPHONE.  Members of
the Board of Directors, or of any committee thereof, may participate in a
meeting of such board or committee by means of conference telephone or similar
communications equipment that enables all persons participating in a meeting to
hear each other.  Such participation shall constitute presence in person at such
meeting for all purposes.

     SECTION 6.  CONDUCT OF BUSINESS.  The act of a majority of the directors
present at a meeting of which a quorum is present shall be the act of the Board
of Directors, except as otherwise provided herein or provided by law.

     SECTION 7.  RESIGNATIONS.  Any director, member of a committee or other
officer may resign at any time.  Such resignation shall be made in writing, and
shall take effect at the time specified therein, and if no time be specified, at
the time of its receipt by the President or Secretary.  The acceptance of a
resignation shall not be necessary to make it effective.

     SECTION 8.  VACANCIES.  If the office of any director, member of a
committee or other officer becomes vacant, the remaining directors in office
though less than a quorum by a majority vote, may appoint any qualified person
to fill such vacancy, who shall hold office for the unexpired term and until his
successor shall be duly chosen.

     SECTION 9.  REMOVAL.  Any director or directors may be removed either for
or without cause at any time by the affirmative vote of the holders of a
majority of all the shares of stock outstanding and entitled to vote, at a
special meeting of the stockholders called for this purpose, or by written
consent as provided by law.  Any director or directors may be removed for cause
by the majority vote of the other directors.

     SECTION 10. INCREASE OF NUMBER.  The number of directors may be increased
or decreased by amendment of these By-Laws by the affirmative vote of a majority
of the directors, though less than a quorum, or, by the affirmative vote of a
majority in interest of the stockholders, at the annual meeting or at a special
meeting called for that purpose, and by like vote the additional directors may
be chosen at such meeting to hold office until the next annual election and
until their successors are elected and qualified.

     SECTION 11. COMPENSATION.  Directors shall not receive any stated salary
for their services as directors or as member of committees, but by resolution of
the Board of Directors, fixed fees and expenses of attendance may be allowed for
attendance at each meeting.  By resolution of the Board of Directors, directors
may also be granted coverage under the Corporation's health insurance, life
insurance or other benefit plans.  Nothing herein contained shall be construed
to preclude any director from serving the corporation in any other capacity as
an officer, agent or otherwise, and receiving compensation therefor.

     SECTION 12. ACTION WITHOUT MEETING.  Any action required or permitted to
be taken at any meeting of the Board of Directors, or of any committee thereof,
may be taken without a meeting, if prior to such action a written consent
thereto is signed by all members of

                                      -4-
<PAGE>

the board, or of such committee as the case may be, and such written consent is
filed with the minutes of proceedings of the board or committee.

     SECTION 13.  PRESUMPTION OF ASSENT.  A director of the corporation who is
present at a meeting of the Board of Directors at which action on any corporate
matter is taken shall be conclusively presumed to have assented to the action
taken unless his dissent shall be entered in the minutes of the meeting or
unless he shall file his written dissent to such action with the person acting
as the secretary of the meeting before the adjournment thereof or shall forward
such dissent by registered mail to the secretary of the corporation immediately
after the adjournment of the meeting.  Such right to dissent shall not apply to
a director who voted in favor of such action.

     SECTION 14.  RELIANCE ON CORPORATE RECORDS.  A member of the board of
directors, or a member of any committee designated by the board of directors,
shall, in the performance of his duties, be fully protected in relying in good
faith upon the records of the corporation and upon such information, opinions,
reports or statements presented to the corporation by any of the corporation's
officers or employees, or committees of the board of directors, or by any other
person as to matters the member reasonably believes are within such other
person's professional or expert competence and who has been selected with
reasonable care by or on behalf of the corporation.

                                   ARTICLE IV
                                   ----------
                                    OFFICERS
                                    --------

     SECTION 1.  OFFICERS.  The officers of the corporation shall consist of the
President, Secretary and such other officers as determined by the Board of
Directors.  None of the officers of the corporation need be directors.  The
officers shall be elected at the first meeting of the Board of Directors after
each annual meeting.  More than one office may be held by the same person.

     SECTION 2.  SALARIES.  The salaries of the officers shall be fixed from
time to time by the board of directors and no officer shall be prevented from
receiving such salary by reason of the fact that he is also a director of the
corporation.

                                   ARTICLE V
                                   ---------
                                     STOCK
                                     -----

     SECTION 1.  CERTIFICATES OF STOCK.  Every holder of stock in the
corporation shall be entitled to have a certificate, signed by, or in the name
of the corporation by, the chairman or vice-chairman of the board of directors,
or the president or a vice-president and the treasurer or an assistant
treasurer, or the secretary of the corporation, certifying the number of shares
owned by him in the corporation.  The designations, preferences and relative,
participating, optional or other special rights of each class of stock or series
thereof and the qualifications, limitations, or restrictions of such preferences
and/or rights shall be set forth in full or summarized on the face or back of
the certificate which the corporation shall issue to represent such class or
series of stock provided that, except as otherwise provided in Section 202 of
the General Corporation Law of Delaware, in lieu of the foregoing requirements,
there may be

                                      -5-
<PAGE>

set forth on the face or back of the certificate which the corporation shall
issue to represent such class or series of stock, a statement that the
corporation will furnish without charge to each stockholder who so requests the
powers, designations, preferences and relative, participating, optional or other
special rights of each class of stock or series thereof and the qualifications,
limitations or restrictions of such preferences and/or rights. Where a
certificate is countersigned (1) by a transfer agent other than the corporation
or its employee, or (2) by a registrar other than the corporation or its
employee, the signatures of such officers may be facsimiles.

     SECTION 2.  LOST CERTIFICATES.  New certificates of stock may be issued in
the place of any certificate issued by the corporation, alleged to have been
lost or destroyed, and the directors may, in their discretion, require the owner
of the lost or destroyed certificate or his legal representatives, to give the
corporation a bond, in such sum as they may direct, not exceeding double the
value of the stock, to indemnify the corporation against it on account of the
alleged loss of any such new certificate.

     SECTION 3.  TRANSFER OF SHARES.  The shares of stock of the corporation
shall be transferable only upon its books by the holders thereof in person or by
their duly authorized attorneys or legal representatives, and upon such transfer
the old certificates shall be surrendered to the corporation by the delivery
thereof to the person in charge of the stock and transfer books and ledgers, or
to such other persons as the directors may designate, by who they shall be
canceled, and new certificates shall thereupon be issued.  A record shall be
made of each transfer and whenever a transfer shall be made for collateral
security, and not absolutely, it shall be so expressed in the entry of the
transfer.

     SECTION 4.  RETIREMENT OF STOCK.  The corporation, by resolution of its
board of directors, may retire any shares of its capital stock that are issued
but are not outstanding.

     Whenever any shares of the capital stock of this corporation are retired,
they shall resume the status of authorized and unissued shares of the class or
series to which they belong unless the certificate of incorporation otherwise
provides.

     SECTION 5.  DIVIDENDS.  Subject to the provisions of the Certificate of
Incorporation, the Board of Directors may, out of funds legally available
therefor at any regular or special meeting, declare and pay dividends upon the
shares of its capital stock.

                                  ARTICLE VI
                                  ----------
                                  FISCAL YEAR
                                  -----------

     SECTION 1.  FISCAL YEAR.  The fiscal year of the corporation shall be
determined by resolution of the Board of Directors.

                                  ARTICLE VII
                                  -----------
                                    NOTICES
                                    -------

     SECTION 1.  NOTICES.  Whenever notice is required to be given to any
stockholder, director, officer or agent, such requirement shall not be construed
to mean personal notice.  Such notice may in any instance be effectively given
by depositing a writing in a post office or letter box in a pre-paid, sealed
wrapper, or by dispatching a pre-paid telegram, addressed to such

                                      -6-
<PAGE>

stockholder, director, officer or agent at his or her address as the same
appears on the books of the corporation. The time when such notice is dispatched
shall be the time of the giving of the notice.

     SECTION 2.  WAIVERS.  A written waiver of any notice, signed by a
stockholder, director, officer or agent, whether before or after the time of the
event for which notice is to be given, shall be deemed equivalent to the notice
required to be given to such stockholder, director, officer or agent.  Neither
the business nor the purpose of any meeting need to be specified in such a
waiver.

                                  ARTICLE VIII
                                  ------------
                                   AMENDMENTS
                                   ----------

     SECTION 1.  These By-Laws may be amended and/or repealed and new or
additional By-Laws may be made at any annual meeting of the stockholders or at
any special meeting thereof if notice thereof is contained in the notice of such
special meeting by the affirmative vote of a majority of the stock issued and
outstanding or entitled to vote thereat, or by the regular meeting of the Board
of Directors, or at any special meeting of the Board of Directors, if notice
thereof is contained in the notice of such special meeting.

     SECTION 2.  A resolution authorizing a proposed amendment to the
certificate of incorporation may provide that at any time prior to the filing of
the amendment with the Secretary of State, notwithstanding authorization of the
proposed amendment by the stockholders of the corporation or by the members of a
nonstock corporation, the board of directors or governing body may abandon such
proposed amendment without further action by the stockholders or members.

                                   ARTICLE IX
                                   ----------
                          INDEMNIFICATION OF OFFICERS
                        DIRECTORS, EMPLOYEES AND AGENTS
                        -------------------------------

     SECTION 1.  The corporation shall indemnify any person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding, whether civil, criminal, administrative or
investigative (other than an action by or in the right of the corporation) by
reason of the fact that he is or was a director or officer of the corporation or
is or was serving at the request of the corporation as a director or officer of
another corporation, against expenses (including attorneys' fees), judgments,
fines and amounts paid in settlement actually and reasonably incurred by him in
connection with such action, suit or proceeding if he acted in good faith and in
a manner he reasonably believed to be in or not opposed to the best interests of
the corporation, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful.  The termination of any
action, suit or proceeding by judgment, order, settlement, conviction or upon a
plea of nolo contendere or its equivalent, shall not, of itself, create a
presumption that the person did not act in good faith and in a manner which he
reasonably believed to be in or not opposed to the best interests of the
corporation, and with respect to any criminal action or proceeding, had
reasonable cause to believe that his conduct was unlawful.

                                      -7-
<PAGE>

     SECTION 2.  The corporation shall indemnify any person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action or suit by or in the right of the corporation to procure a
judgment in its favor by reason of the fact that he is or was a director or
officer of the corporation, or is or was serving at the request of the
corporation as a director or officer of another corporation, against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection with the defense or settlement of such action or suit if he acted in
good faith and in a manner he reasonably believed to be in or not opposed to the
best interests of the corporation except that no indemnification shall be made
in respect of any claim, issue or matter as to which such person shall have been
adjudged to be liable to the corporation, unless and only to the extent that the
Court of Chancery or the court in which such action or suit was brought shall
determine upon application that despite the adjudication of liability but in
view of all the circumstances of the case, such person is fairly and reasonably
entitled to indemnity for such expenses which the Court of Chancery or such
other court shall deem proper.

     SECTION 3.  No director of the corporation shall be liable to the
corporation or its stockholders for monetary damages for breach of fiduciary
duty as a director, except for liability for (a) any breach of the director's
duty of loyalty to the corporation or its stockholders; (b) acts or omissions
not in good faith or which involve intentional misconduct or a knowing violation
of law; (c) acts under Section 174 of the Delaware General Corporation Law; or
(d) any transaction from which the director derived an improper personal
benefit.

     SECTION 4.  Expenses incurred in defending a civil or criminal action, suit
or proceeding may be paid by the corporation in advance of the final disposition
of such action, suit or proceeding as authorized by the board of directors in
the specific case upon receipt of an undertaking by or on behalf of the director
or officer, to repay such amount unless it shall ultimately be determined that
he is not entitled to be indemnified by the corporation as authorized in this
Article Ninth.  Such expenses (including attorneys' fees) incurred by other
employees or agents may be so paid upon such terms and conditions, if any, as
the board of directors deems appropriate.

     SECTION 5.  Any indemnification under Section (1) and (2) above (unless
ordered by a Court) shall be made by the corporation only as authorized in the
specific case upon a determination that indemnification of the director or
officer is proper in the circumstances because he has met the applicable
standard of conduct set forth in Sections (1) and (2).  Such determination shall
be made (a) by the board of directors by a majority vote of a quorum consisting
of directors who were not parties to such action, suit or proceeding, or (b) if
such a quorum is not obtainable, or, even if obtainable and a quorum of
disinterested directors so directs, by independent legal counsel in a written
opinion, or (c) by the stockholders.

     SECTION 6.  The indemnification provided by this Article IX shall not be
deemed exclusive of any other rights to which those seeking indemnification or
advancement of expenses may be entitled under any by-laws, agreement, vote of
stockholders or disinterested directors or otherwise, both as to action in
another capacity while holding such office, and shall continue as to a person
who has ceased to be a director or officer and shall inure to the benefit of the
heirs, executors and administrators of such a person.

                                      -8-
<PAGE>

     SECTION 7.  The corporation shall have the power to purchase and maintain
insurance on behalf of any person who is or was a director or officer of the
corporation or is or was serving at the request of the corporation as a director
or officer of another corporation, against any liability asserted against him
and incurred by him in any such capacity, or arising out of his status as such,
whether or not the corporation would have the power to indemnify him against
such liability under the provisions of this Article IX.

     SECTION 8.  For the purposes of this Article IX, reference to "the
corporation" shall include all constituent corporations absorbed in a
consolidation or merger as well as the resulting or surviving corporation so
that any person who is or was a director or officer of such a constituent
corporation or is or was serving at the request of such constituent corporation
or other enterprise shall stand in the same position under the provisions of
this section with respect to the resulting or surviving corporation in the same
capacity.