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                                                                    EXHIBIT 10.3

                       NATURAL MICROSYSTEMS CORPORATION
                     1995 NON-STATUTORY STOCK OPTION PLAN
              (As Amended and Restated Effective March 12, 1999)


     1.  PURPOSE.  The purpose of this Natural MicroSystems Corporation 1995
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Non-Statutory Stock Option Plan (the "Plan") is to provide an incentive to
certain employees (other than executive officers, who are not eligible to
participate in the Plan) of and consultants to Natural MicroSystems Corporation
(the "Company") or any of its subsidiaries by providing them an opportunity to
participate in the ownership of the Company.  This Plan provides for the grant
of non-statutory stock options (i.e., stock options which are not intended to
qualify as incentive stock options as defined in Section 422 of the Internal
Revenue Code of 1986, as amended (the "Code")) to non-executive officer
employees of and consultants to the Company or any of its subsidiaries.  All
such stock options which may be granted under this Plan are hereinafter referred
to as "Options."

     2.  ADMINISTRATION OF THE PLAN.  This Plan shall be administered by the
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Board of Directors of the Company (the "Board").  Subject to the provisions of
Section 14, the Board is authorized to interpret the Plan, to prescribe, amend
and rescind rules and regulations relating to it, and to make all other
determinations necessary or advisable for its administration.  The Board shall
have the right, at its discretion, to delegate any and all of its powers
hereunder to the Chief Executive Officer ("CEO") of the Company (excluding, as
to such officer, any power in respect of Options granted or to be granted to
officers of the Company) or to a Committee appointed by the Board.  If the Board
delegates its powers to the CEO or a Committee, in whole or in part, the CEO's
or Committee's determinations with respect thereto shall not be subject to
approval by the Board, and to the extent of such delegation, references in this
Plan to the Board shall be deemed to refer to the CEO or the Committee.

     3.  SHARES COVERED BY THE PLAN.  Options may be granted under the Plan
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while the Plan is in effect for the purchase of not in excess of 1,800,000
shares of the Common Stock, $.01 par value ("Common Stock"), of the Company
(subject to adjustment as provided in Section 11 hereof).  Shares covered by
unexercised Options which are no longer exercisable for any reason shall be
available for issuance under Options granted hereunder for purposes of computing
the foregoing limitation unless the Plan has been terminated.  Shares delivered
on exercise of Options may be made available from authorized and unissued Common
Stock or from Common Stock held in the Treasury of the Company.  In connection
with the grant of any Option under the Plan, the Board may in its discretion
provide for a cash payment to be made to the person exercising the Option, at
the time of exercise, in such amount as the Board determines to be appropriate
to reimburse such person, in whole or in part, for any federal or state income
taxes incurred in connection with such exercise.  Such payment may be applied to
the satisfaction of any applicable withholding tax which is incurred in
connection with such exercise or with such payment.
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     4.  ELIGIBILITY.  The persons who shall be eligible to receive Options
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under the Plan shall be non-executive officer employees of and consultants to
the Company or any of its subsidiaries.  Such persons are hereinafter referred
to as "Eligible Individuals."

     5.  ALLOTMENT OF OPTIONS AND NUMBER OF SHARES.  The allotment of Options
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among the Eligible Individuals, the number of shares to be covered by each
Option to be granted shall be determined by the Board.

     6.  OPTION AGREEMENTS.  Each Eligible Individual to whom an Option is
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granted (an "Optionee") shall enter into a written agreement with the Company
setting forth the terms and conditions of the Option granted to him, which
agreement may contain such terms, conditions and restrictions not inconsistent
with the terms of the Plan as the Board shall approve.

     7.  OPTION PRICE.  The price to be paid by an Optionee who exercises an
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Option shall be determined by the Board; provided that in no event shall the
price be less than the fair market value of the Common Stock on the date the
Option is granted.

     8.  DURATION AND RATE OF EXERCISE OF OPTIONS.  The option period shall be
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fixed by the Board but in any event each Option shall by its terms be
exercisable no later than the expiration of ten years from the date the Option
is granted. The Board shall determine the rate at which each Option shall be
exercisable, provided that in no event shall an Option be exercisable at a rate
greater than 12.5% of the shares under the Option per quarter, subject to
acceleration thereof only in connection with a merger in which the Company is
not the surviving corporation, a disposition of substantially all its assets, a
change of control, or similar extraordinary event.

     The Board shall determine the manner in which each Option shall be
exercisable, the timing and form of the purchase price to be paid by an Optionee
upon the exercise of an Option, and any restrictions to be imposed upon the
Common Stock received on exercise of an Option.  To the extent provided in the
option agreement, payment of the purchase price may be entirely in cash, part in
cash and part by personal promissory note or in whole or in part by the
surrender of a whole number of shares of previously issued Common Stock of the
Company.  Previously issued shares of Common Stock shall be accepted as payment
in an amount equal to the then fair market value of the surrendered shares.

     9.  NONTRANSFERABILITY OF OPTIONS.  Each Option granted under the Plan to
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any Eligible Individual shall by its terms not be transferable by him otherwise
than by will or the laws of descent and distribution, and shall be exercisable
during his lifetime only by him.

     10. RIGHTS AS A STOCKHOLDER.  An Optionee shall have no rights as a
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stockholder with respect to any shares covered by his Options until he shall
have become the holder of record of such shares, and no adjustment shall be
made, except adjustments pursuant to Section 11 hereof, for dividends (ordinary
or extraordinary, whether in cash, securities or other

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property) or distributions or other rights in respect of such shares for which
the record date is prior to the date on which he shall have become the holder of
record thereof.

     11.  EFFECT OF CHANGE IN STOCK SUBJECT TO THE PLAN.  In the event there is
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any change in the shares of Common Stock of the Company through the declaration
of stock dividends or through recapitalizations resulting in stock subdivisions
or combinations or exchanges of shares or otherwise, the number of shares
available for Option, the exercise price of outstanding Options, and the number
of shares subject to any Option shall be appropriately adjusted by the Board.
If the Company is merged into or consolidated with another corporation under
circumstances where the Company is not the surviving corporation, or if the
Company is liquidated or sells or otherwise disposes of substantially all of its
assets to another corporation while unexercised Options remain outstanding, (i)
subject to the provisions of clauses (iii) and (iv) below, after the effective
date of such merger, consolidation or sale, as the case may be, each holder of
an outstanding Option shall be entitled, upon exercise of such Option, to
receive in lieu of shares of Common Stock, shares of such stock or other
securities as the holders of shares of Common Stock received pursuant to the
terms of the merger, consolidation or sale; or (ii) the Board may waive any
discretionary limitations imposed pursuant to Section 8 hereof so that all
Options from and after a date prior to the effective date of such merger,
consolidation, liquidation or sale, as the case may be, specified by the Board,
shall be exercisable in full; or (iii) all outstanding Options may be cancelled
by the Board as of the effective date of any such merger, consolidation,
liquidation or sale provided that notice of such cancellation shall be given to
each holder of an Option, and each holder of an Option shall have the right to
exercise such Option in full (without regard to any discretionary limitations
imposed pursuant to Section 8 hereof) during a 30-day period preceding the
effective date of such merger, consolidation, liquidation or sale; or (iv) all
outstanding Options may be cancelled by the Board as of the date of any such
merger, consolidation, liquidation or sale provided that notice of such
cancellation shall be given to each holder of an Option, and each holder of an
Option shall have the right to exercise such Option but only to the extent
exercisable in accordance with any discretionary limitations imposed pursuant to
Section 8 prior to the effective date of such merger, consolidation, liquidation
or sale.

     12.  GRANT OF OPTIONS IN CONNECTION WITH CERTAIN ACQUISITIONS.  The Board
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may grant Options under the Plan in substitution of stock options granted under
plans of other employers, if such grant occurs by reason of a corporate merger,
consolidation, separation, reorganization, or liquidation to which the Company
is a party, or by reason of the acquisition of property or stock of another
corporation by the Company.

     13.  USE OF PROCEEDS.  The proceeds received by the Company from the sale
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of Common Stock pursuant to the Plan may be used for general corporate purposes.

     14.  AMENDMENT AND DISCONTINUANCE.  The Board may from time to time alter
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or suspend and at any time discontinue the Plan.  However, no action of the
Board may alter or impair an Optionee's rights under any outstanding Option
previously granted under the Plan, without the consent of the holder of the
Option.

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     15.  EFFECTIVE DATE AND TERMINATION DATE.  The Plan shall become effective
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and shall be deemed to have been adopted on October 27, 1995, the date of its
adoption by the Board.  The Plan shall remain in effect until terminated by the
Board, but not later than October 26, 2005.  Amended by the Board of Directors
on:

     March 8, 1996
     December 19, 1996
     April 16, 1998
     March 12, 1999

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