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                                                                     EXHIBIT 3.6

                               SIRONE CORPORATION

                                     BY-LAWS

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                                     SIRONE

                                   CORPORATION

                                     By-Laws

                               ARTICLE I - OFFICES

      Section 1. The registered office of the corporation in the State of
Delaware shall be at 1013 Centre Road, Wilmington, Delaware 19899.

      The registered agent in charge thereof shall be Corporation Service
Company.

      Section 2. The corporation may also have offices at such other places as
the Board of Directors may from time to time appoint or the business of the
corporation may require.

                                ARTICLE II - SEAL

      Section 1. The corporate seal shall have inscribed thereon the name of the
corporation , the year of its organization and the words "Corporate Seal,
Delaware".

                      ARTICLE III - STOCKHOLDERS' MEETINGS

      Section 1. Meetings of stockholders shall be held at the registered office
of the corporation in this state or at such place, either within or without this
state, as may be selected from time to time by the Board of Directors.

      Section 2. Annual Meetings: The annual meeting of the stockholders shall
be held on the fourth day of November in each year if not a legal holiday, and
if a legal holiday, then on the next secular day following at three o'clock
P.M., when they shall elect a Board of Directors and transact such other
business as may properly be brought


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By-Laws
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before the meeting. If the annual meeting for election of directors is not held
on the date designated therefor, the directors shall cause the meeting to be
held as soon thereafter as convenient.

      Section 3. Election of Directors: Elections of the directors of the
corporation shall be by written ballot.

      Section 4. Special Meetings: Special meetings of the stockholders may be
called at any time by the President, or the Board of Directors, or stockholders
entitled to cast at least one-fifth of the votes which all stockholders are
entitled to cast at the particular meeting. At any time, upon written request of
any person or persons who have duly called a special meeting, it shall be the
duty of the Secretary to fix the date of the meeting, to be held not more than
sixty days after receipt of the request, and to give due notice thereof. If the
Secretary shall neglect or refuse to fix the date of the meeting and give notice
thereof, the person or persons calling the meeting may do so.

      Business transacted at all special meetings shall be confined to the
objects stated in the call and matters germane thereto, unless all stockholders
entitled to vote are present and consent.

      Written notice of a special meeting of stockholders stating the time and
place and object thereof, shall be given to each stockholders entitled to vote
thereat at least ten days before such meeting, unless a greater period of notice
is required by statute in a particular case,

      Section 5. Quorum: One-third of the outstanding shares of the corporation
entitled to vote, represented in person or by proxy , shall constitute a quorum
at a


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meeting of stockholders. If less than one-third of the outstanding shares
entitled to vote is represented at a meeting, a majority of the shares so
represented may adjourn the meeting from time to time without further notice. At
such adjourned meeting at which a quorum shall be present or represented, any
business may be transacted which might have been transacted at the meeting as
originally noticed. The stockholders present at a duly organized meeting may
continue to transact business until adjournment, notwithstanding the withdrawal
of enough stockholders to leave less than a quorum.

      Section 6. Proxies: Each stockholder entitled to vote at a meeting of
stockholders or to express consent or dissent to corporate action in writing
without a meeting may authorize another person or persons to act for him by
proxy, but no such proxy shall be voted or acted upon after three years from its
date, unless the proxy provides for a longer period.

      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. All
proxies shall be filed with the Secretary of the meeting before being voted
upon.

      Section 7. Notice of Meetings: Whenever stockholders are required or
permitted to take an action at a meeting, a written notice of the meeting shall
be given


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which shall state the place, date and hour of the meeting, and, in the case of a
special meeting, the purpose or purposes for which the meeting is called.

      Unless otherwise provided by law, written notice of any meeting shall be
given not less than ten nor more than sixty days before the date of the meeting
to each stockholder entitled to vote at such meeting.

      Section 8. Consent in Lieu of Meetings: Any action required to be taken at
any annual or special meeting of stockholders of a corporation, or any action
which may be taken at any annual or special meeting of such stockholders, may be
taken without a meeting, without prior notice and without a vote, if a consent
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. Prompt notice of the taking of
the corporate action without a meeting by less than unanimous written consent
shall be given to those stockholders who have not consented in writing.

      Section 9. List of Stockholders: The officer who has charge of the stock
ledger of the corporation shall prepare and make, at least ten days before every
meeting of stockholders, a complete.list of the stockholders entitled to vote at
the meeting, arranged in alphabetical order, and showing the address of each
stockholder and the number of shares registered in the name of each stockholder.
No share of stock upon which any installment is due and unpaid shall be voted at
any meeting. The list shall be open to the examination of any stockholder, for
any purpose germane

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to the meeting, during ordinary business hours, for a period of at least ten
days prior to the meeting, either at a place within the city where the meeting
is to be held, which place shall be specified in the notice of the meeting, or
if not so specified, at the place where the meeting is to be held. The list
shall also be produced and kept at the time and place of the meeting during the
whole time thereof, and may be inspected by any stockholder who is present.

                             ARTICLE IV - DIRECTORS

      Section 1. The business and affairs of this corporation shall be managed
by its Board of Directors, three in number. The directors need not be residents
of this state or stockholders in the corporation. They shall be elected by the
stockholders at the annual meeting of the corporation, and each director shall
be elected for the term of one year, and until his successor shall be elected
and shall qualify or until his earlier resignation or removal.

      Section 2. Regular Meetings: Regular meetings of the Board shall be held
without notice at the registered office of the corporation, or at such other
time and place as shall be determined by the Board.

      Section 3. Special Meetings: Special Meetings of the Board may be called
by the President on three days notice to each director, either personally or by
mail or by telegram. Special meetings shall be called by the President or
Secretary in like manner and on like notice on the written request of a majority
of the directors in office.


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      Section 4. Quorum: A majority of the total number of directors shall
constitute a quorum for the transaction of business.

      Section 5. Consent in Lieu of Meetings: 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 all members of the Board or
committee, as the case may be, consent thereto in writing, and the writing or
writings are filed with the minutes of proceedings of the Board or committee.
The Board of Directors may hold its meetings, and have an office, or offices,
outside of this state.

      Section 6. Conference Telephone: One or more directors may participate in
a meeting of the Board, of a committee of the Board or of the stockholders, by
means of conference telephone or similar communications equipment by means of
which all persons participation in the meeting can hear each other.
Participation in this manner shall constitute presence in person at such
meeting.

      Section 7. Compensation: Directors as such, shall not receive any stated
salary for their services, but by resolution of the Board, a FIXED sum and
expenses of attendance, if any, may be allowed for attendance at each regular or
special meeting of the Board PROVIDED, that nothing herein contained shall be
construed to preclude any director from serving the corporation in any other
capacity and receiving compensation therefor.

      Section 8. Removal: Any director or the entire Board of Directors may be
removed, with or without cause, by the holders of a majority of the shares then
entitled to vote at an election of directors, except that when cumulative voting
is


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permitted, if less than the entire Board is to be removed, no director may be
removed without cause if the votes cast against his removal would be sufficient
to elect him if then cumulatively voted at an election of the entire Board of
Directors, or, if there be classes of directors, at an election of the class of
directors of which he is a part.

                              ARTICLE V - OFFICERS

      Section 1. The executive officers of the corporation shall be chosen by
the directors and shall be a President, Secretary and Treasurer. The Board of
Directors may also choose a Chairman, one or more Vice Presidents and such other
officers as it shall deem necessary. Any number of offices may be held by the
same person.

      Section 2. Salaries: Salaries of all officers and agents of the
corporation shall be fixed by the Board of Directors.

      Section 3. Term of Office: The officers of the corporation shall hold
office for one year and until their successors are chosen and have qualified.
Any officer or agent elected or appointed by the Board may be removed by the
Board of Directors whenever in its judgment the best interest of the corporation
will be served thereby.

      Section 4. President: The President shall be the chief executive officer
of the corporation; he shall preside at all meetings of the stockholders and
directors; he shall have general and active management of the business of the
corporation, shall see that all orders and resolutions of the Board are carried
into effect, subject, however, to the right of the directors to delegate any
specific powers, except such as may be by statute exclusively conferred on the
President, to any other officer or officers of the


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corporation. He shall execute bonds, mortgages and other contracts requiring a
seal, under the seal of the corporation. He shall be EX-OFFICIO a member of all
committees, and shall have the general power and duties of supervision and
management usually vested in the office of President of a corporation.

      Section 5. Secretary: The Secretary shall attend all sessions of the Board
and all meetings of the stockholders and act as clerk thereof, and record all
the votes of the corporation and the minutes of all its transactions in a book
to be kept for that purpose, and shall perform like duties for all committees of
the Board of Directors when required. He shall give, or cause to be given,
notice of all meetings of the stockholders and of the Board of Directors, and
shall perform such other duties as may be prescribed by the Board of Directors
or President, and under whose supervision he shall be. He shall keep in safe
custody the corporate seal of the corporations, and when authorized by the
Board, affix the same to any instrument requiring it.

      Section 6. Treasurer: The Treasurer shall have custody of the corporate
funds and securities and shall keep full and accurate accounts of receipts and
disbursements in books belonging to the corporation, and shall keep the moneys
of the corporation in a separate account to the credit of the corporation. He
shall disburse the funds of the corporation as may be ordered by the Board,
taking proper vouchers for such disbursements, and shall render to the President
and directors, at the regular meetings of the Board, or whenever they may
require it, an account of all his transactions as Treasurer and of the financial
condition of the corporation.


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                             ARTICLE VI - VACANCIES

      Section 1. Any vacancy occurring in any office of the corporation by
death, resignation, removal or otherwise, shall be filled by the Board of
Directors. Vacancies and newly created directorships resulting from any increase
in the authorized number of directors may be filled by a majority of the
directors then in office, although less than a quorum, or by a sole remaining
director. If at any time, by reason of death or resignation or other cause, the
corporation should have no directors in office, then any officer or any
stockholder or an executor, administrator, trustee or guardian of a stockholder,
or other fiduciary entrusted with like responsibility for the person or estate
of a stockholder, may call a special meeting of stockholders in accordance with
the provisions of these By-Laws.

      Section 2. Resignations Effective at Future Date: When one or more
directors shall resign from the Board, effective at a future date, a majority of
the directors then in office, including those who have so resigned, shall have
power to fill such vacancy or vacancies, the vote thereon to take effect when
such resignation or resignations shall become effective.

                         ARTICLE VII - CORPORATE RECORDS

      Section 1. Any stockholder of record, in person or by attorney or other
agent, shall, upon written demand under oath stating the purpose thereof, have
the right


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during the usual hours for business to inspect for any proper purpose the
corporation's stock ledger, a list of its stockholders, and its other books and
records, and to make copies or extracts therefrom. A proper purpose shall mean a
purpose reasonably related to such person's interest as a stockholder. In every
instance where an attorney or other agent shall be the person who seeks the
right to inspection, the demand under oath shall be accompanied by a power of
attorney or such other writing which authorizes the attorney or other agent to
so act on behalf of the stockholder. The demand under oath shall be directed to
the corporation at its registered office in this state or at its principal place
of business.

               ARTICLE VIII - STOCK CERTIFICATES, DIVIDENDS, ETC.

      Section 1. The stock certificates of the corporation shall be numbered and
registered in the share ledger and transfer books of the corporation as they are
issued. They shall bear the corporate seal and shall be signed by the President
and the Secretary.

      Section 2. Transfers: Transfers of shares shall be made on the books of
the corporation upon surrender of the certificate or by a power of attorney,
lawfully constituted in writing. No transfer shall be made which is inconsistent
with law.

      Section 3. Lost Certificate: The corporation may issue a new certificate
of stock in the place of any certificate theretofore signed by it, alleged to
have been lost, stolen or destroyed, and the corporation may require the owner
of the lost, stolen or destroyed certificate, or his legal representative to
give the corporation a bond


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sufficient to indemnify it against any claim that may be made against it on
account of the alleged loss, theft or destruction of any such certificate or the
issuance of such new certificate.

      Section 4. Record Date: In order that the corporation may determine the
stockholders entitled to notice of or to vote at any meeting of stockholders or
any adjournment thereof, or to express consent to corporate action in writing
without a meeting, or entitled to receive payment of any dividend or other
distribution or allotment of any rights, or entitled to exercise any rights in
respect of any change, conversion or exchange of stock or for the purpose of any
other lawful action, the Board of Directors may f@ in advance, a record date,
which shall not be more than sixty nor less than ten days before the date of
such meeting, nor more than sixty days prior to any other action.

      If no record date is fixed:

            (a) The record date for determining stockholders entitled to notice
      of or to vote at a meeting of stockholders shall be at the close of
      business on the day next preceding the day on which notice is given, or,
      if notice is waived, at the close of business on the day next preceding
      the day on which the meeting is held.

            (b) The record date for determining stockholders entitled to express
      consent to corporate action in writing without a meeting, when no prior
      action by the Board of Directors is necessary, shall be the day on which
      the first written consent is expressed.


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            (c) The record date for determining stockholders for any other
      purpose shall be at the close of business on the day on which the Board of
      Directors adopts the resolution relating thereto.

            (d) A determination of stockholders of record entitled to notice of
      or to vote at a meeting of stockholders shall apply to any adjournment of
      the meeting; provided, however, that the Board of Directors may fix a new
      record date for the adjourned meeting. 

      Section 5. Dividends: The Board of Directors may declare and pay dividends
upon the outstanding shares of the corporation from time to time and to such
extent as they deem advisable, in the manner and upon the terms and conditions
provided by statute and the Certificate of Incorporation.

      Section 6. Reserves: Before payment of any dividend there may be set aside
out of the net profits of the corporation such sum or sums as the directors,
from time to time, in their absolute discretion, think proper as a reserve fund
to meet contingencies, or for equalizing dividends, or for repairing or
maintaining any property of the corporation, or for such other purpose as the
directors shall think conducive to the interests of the corporation, and the
directors may abolish any such reserve in the manner in which it was created.

                      ARTICLE IX - MISCELLANEOUS PROVISIONS


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      Section 1. Checks: All checks or demands for money and notes of the
corporation shall be signed by such officer or officers as the Board of
Directors may from time to time designate.

      Section 2. Fiscal Year: The fiscal year shall begin on the first day of
January.

      Section 3. Notice: Whenever written notice is required to be given to any
person, it may be given to such person, either personally or by sending a copy
thereof through the mail, or by telegram, charges prepaid, to his address
appearing on the books of the corporation, or supplied by him to the corporation
for the purpose of notice. If the notice is sent by mail or by telegraph, it
shall be deemed to have been given to the person entitled thereto when deposited
in the United States mail or with a telegraph office for transmission to such
person. Such notice shall specify the place, day and hour of the meeting and, in
the case of a special meeting of stockholders, the general nature of the
business to be transacted.

      Section 4. Waiver of Notice: Whenever any written notice is required by
statute, or by the Certificate or the By-Laws of this corporation a waiver
thereof in writing, signed by the person or persons entitled to such notice,
whether before. or after the item stated therein, shall be deemed equivalent to
the signing of such notice. Except in the case of a special meeting of
stockholders, neither the business to be transacted at nor the purpose of the
meeting need be specified in the waiver of notice of such meeting. Attendance of
a person either in person or by proxy, at any meeting shall constitute a waiver
of notice of such meeting, except where a person attends a


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meeting for the express purpose of objecting to the transaction of any business
because the meeting was not lawfully called or convened.

      Section 5. Disallowed Compensation: Any payments made to an officer or
employee of the corporation such as a salary, commission, bonus, interest, rent,
travel or entertainment expense incurred by him, which shall be disallowed in
whole or in part as a deductible expense by the Internal Revenue Service, shall
be reimbursed by such officer or employee to the corporation to the full extent
of such disallowance. It shall be the duty of the directors, as a Board, to
enforce payment of each such amount disallowed. In lieu of payment by the
officer or employee, subject to the determination of the directors,
proportionate amounts may be withheld from his future compensation payments
until the amount owed to the corporation has been recovered.

      Section 6. Resignations: Any director or other officer may resign at
anytime, such resignation to be in writing, and to take effect from the time of
its receipt by the corporation, unless some time be fixed in the resignation and
then from that date. The acceptance of a resignation shall not be required to
make it effective.

                          ARTICLE X - ANNUAL STATEMENT

      Section 1. The President and Board of Directors shall present at each
annual meeting a full and complete statement of the business and affairs of the
corporation for the preceding year. Such statement shall be prepared and
presented in whatever


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manner the Board of Directors shall deem advisable and need not be verified by a
certified public accountant.

                             ARTICLE XI - AMENDMENTS

      Section 1. These By-Laws may be amended or repealed by the Board of
Directors at any Directors Meeting.

November 4, 1988

                                         /s/ Rose Ann Balden
                                         ---------------------------------------
                                         Secretary


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