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                                                                   EXHIBIT 10.42




                                SUMMA FOUR, INC.

                             1995 STOCK OPTION PLAN

                        Adopted by the Board of Directors
                                 on May 30, 1995



1.       PURPOSE.

         The purpose of this plan (the "Plan") is to secure for Summa Four, Inc.
(the "Company") and its stockholders the benefits arising from capital stock
ownership by employees and officers of, and consultants or advisors to, the
Company and its subsidiary corporations who are expected to contribute to the
Company's future growth and success. Except where the context otherwise
requires, the term "Company" shall include the parent and all present and future
subsidiaries of the Company as defined in Sections 424(e) and 424(f) of the
Internal Revenue Code of 1986, as amended or replaced from time to time (the
"Code") . Those provisions of the Plan which make express reference to Section
422 shall apply only to Incentive Stock Options (as that term is defined in the
Plan).

2.       TYPE OF OPTIONS AND ADMINISTRATION.

         (a)      TYPES OF OPTIONS. Options granted pursuant to the Plan may be
either incentive stock options ("Incentive Stock Options") meeting the
requirements of Section 422 of the Code or Non-Statutory Options which are not
intended to meet the requirements of Section 422 of the Code ("Non-Statutory
Options").

         (b)      ADMINISTRATION.

                  (i)      The Plan will be administered by the Board of
         Directors of the Company, whose construction and interpretation of the
         terms and provisions of the Plan shall be final and conclusive. The
         Board of Directors may in its sole discretion grant options to purchase
         shares of the Company's Common Stock ("Common Stock") and issue shares
         upon exercise of such options as provided in the Plan. The Board shall
         have authority, subject to the express provisions of the Plan, to
         construe the respective option agreements and the Plan, to prescribe,
         amend and rescind rules and regulations relating to the Plan, to
         determine the terms and provisions of the respective option agreements,
         which need not be identical, and to make all other determinations which
         are, in the judgment of the Board of Directors, necessary or desirable
         for the administration of the Plan. The Board of Directors may correct
         any defect, supply any omission or reconcile any inconsistency in the
         Plan or in any option agreement in the manner and to the extent it
         shall deem expedient to carry the Plan into effect and it shall be the
         sole and final judge of such expediency. No director or person acting
         pursuant to authority delegated by



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         the Board of Directors shall be liable for any action or determination
         under the Plan made in good faith.

                  (ii)     The Board of Directors may, to the full extent
         permitted by or consistent with applicable laws or regulations and
         Section 3(b) of this Plan delegate any or all of its powers under the
         Plan to a committee (the "Committee") appointed by the Board of
         Directors, and if the Committee is so appointed all references to the
         Board of Directors in the Plan shall mean and relate to such Committee.

         (c)      APPLICABILITY OF RULE 16b-3. Those provisions of the Plan
which make express reference to Rule 16b-3 promulgated under the Securities
Exchange Act of 1934 (the "Exchange Act"), or any successor rule ("Rule 16b-3"),
or which are required in order for certain option transactions to qualify for
exemption under Rule 16b-3, shall apply only to such persons as are required to
file reports under Section 16(a) of the Exchange Act (a "Reporting Person").

3.       ELIGIBILITY.

         (a)      GENERAL. Options may be granted to persons who are, at the
time of grant, employees (including employees who are directors of the Company)
or officers of, or consultants or advisors to, the Company; PROVIDED, that the
class of employees to whom Incentive Stock Options may be granted shall be
limited to all employees of the Company. A person who has been granted an option
may, if he or she is otherwise eligible, be granted additional options if the
Board of Directors shall so determine. Subject to adjustment as provided in
Section 15 below, the maximum number of shares with respect to which options may
be granted to any employee under the Plan shall not exceed 500,000 shares of
common stock in any one calendar year. For the purpose of calculating such
maximum number, (a) an option shall continue to be treated as outstanding
notwithstanding its repricing, cancellation or expiration and (b) the repricing
of an outstanding option or the issuance of a new option in substitution for a
cancelled option shall be deemed to constitute the grant of a new additional
option separate from the original grant of the option that is repriced or
cancelled.

         (b)      GRANT OF OPTIONS TO OFFICERS. For so long as Common Stock of
the Company is registered under the Exchange Act, the selection of an officer or
an officer who is also a director (as the terms "director" and "officer" are
defined for purposes of Rule 16b-3) as a recipient of an option, the timing of
the option grant, the exercise price of the option and the number of shares
subject to the option shall be determined either (i) by the Board of Directors,
of which all members shall be "disinterested persons" (as hereinafter defined),
or (ii) by two or more directors having full authority to act in the matter,
each of whom shall be a "disinterested person." For the purposes of the Plan, a
director shall be deemed to be a



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"disinterested person" only if such person qualifies as a "disinterested person"
within the meaning of Rule 16b-3, as such term is interpreted from time to time.

4.       STOCK SUBJECT TO PLAN.

         Subject to adjustment as provided in Section 15 below, the maximum
number of shares of Common Stock which may be issued and sold under the Plan is
500,000 shares. If an option granted under the Plan shall expire or terminate
for any reason without having been exercised in full, the unpurchased shares
subject to such option shall again be available for subsequent option grants
under the Plan. If shares issued upon exercise of an option under the Plan are
tendered to the Company in payment of the exercise price of an option granted
under the Plan, such tendered shares shall again be available for subsequent
option grants under the Plan; provided, that in no event shall such shares be
made available for issuance to Reporting Persons or pursuant to exercise of
Incentive Stock Options.

5.       FORMS OF OPTION AGREEMENTS.

         As a condition to the grant of an option under the Plan, each recipient
of an option shall execute an option agreement in such form not inconsistent
with the Plan as may be approved by the Board of Directors. Such option
agreements may differ among recipients.

6.       PURCHASE PRICE.

         (a)      GENERAL. Subject to Section 3(b), the purchase price per share
of stock deliverable upon the exercise of an option shall be determined by the
Board of Directors at the time of grant of such option; provided, however, that
(i) in the case of Incentive Stock Options, the exercise price shall not be less
than 100% of the fair market value of such stock and (ii) in the case of
Non-Statutory Options, the exercise price shall not be less than 75% of the fair
market value of such stock, and (iii) in the case of options described in
Section 11(b), the exercise price shall not be less than 110% of the fair market
value of such stock.

         (b)      PAYMENT OF PURCHASE PRICE. Options granted under the Plan may
provide for the payment of the exercise price by delivery of cash or a check to
the order of the Company in an amount equal to the exercise price of such
options, or, to the extent provided in the applicable option agreement, or
otherwise agreed to by the Company, (i) by delivery to the Company of shares of
Common Stock of the Company already owned by the optionee having a fair market
value equal in amount to the exercise price of the options being exercised or
(ii) by any other means (including, without limitation, by delivery of a
promissory note of the optionee payable on such terms as are specified by the
Board of Directors) which the Board of Directors determines are consistent with
the purpose of the Plan and with applicable



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laws and regulations (including, without limitation, the provisions of
Regulation T promulgated by the Federal Reserve Board). The fair market value of
any shares of the Company's Common Stock or other non-cash consideration which
may be delivered upon exercise of an option shall be determined by the Board of
Directors.

7.       OPTION PERIOD.

         Each option and all rights thereunder shall expire on such date as
shall be set forth in the applicable option agreement, except that, in the case
of an Incentive Stock Option, such date shall not be later than ten years after
the date on which the option is granted and, in all cases, options shall be
subject to earlier termination as provided in the Plan.

8.       EXERCISE OF OPTIONS.

         Each option granted under the Plan shall be exercisable either in full
or in installments at such time or times and during such period as shall be set
forth in the agreement evidencing such option, subject to the provisions of the
Plan.

9.       NONTRANSFERABILITY OF OPTIONS.

         All options granted shall not be assignable or transferable by the
person to whom they are granted, either voluntarily or by operation of law,
except by will or the laws of descent and distribution, and, during the life of
the optionee, shall be exercisable only by the optionee; provided, however, that
Non-Statutory Options may be transferred pursuant to a qualified domestic
relations order (as defined in Rule 16b-3).

10.      EFFECT OF TERMINATION OF EMPLOYMENT OR OTHER RELATIONSHIP.

         Except as provided in Section 11(d) with respect to Incentive Stock
Options, and subject to the provisions of the Plan, the Board of Directors shall
determine the period of time during which an optionee may exercise an option
following (i) the termination of the optionee's employment or other relationship
with the Company or (ii) the death or disability of the optionee. Such periods
shall be set forth in the agreement evidencing such option.

11.      INCENTIVE STOCK OPTIONS.

         Options granted under the Plan which are intended to be Incentive Stock
Options shall be subject to the following additional terms and conditions:




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         (a)      EXPRESS DESIGNATION. All Incentive Stock Options granted under
the Plan shall, at the time of grant, be specifically designated as such in the
option agreement covering such Incentive Stock Options.

         (b)      10% STOCKHOLDER. If any employee to whom an Incentive Stock
Option is to be granted under the Plan is, at the time of the grant of such
option, the owner of stock possessing more than 10% of the total combined voting
power of all classes of stock of the Company (after taking into account the
attribution of stock ownership rules of Section 424(d) of the Code), then the
following special provisions shall be applicable to the Incentive Stock Option
granted to such individual:

                  (i)      The purchase price per share of the Common Stock
         subject to such Incentive Stock Option shall not be less than 110% of
         the fair market value of one share of Common Stock at the time of
         grant; and

                  (ii)     the option exercise period shall not exceed five
         years from the date of grant.

         (c)      DOLLAR LIMITATION. For so long as the Code shall so provide,
options granted to any employee under the Plan (and any other incentive stock
option plans of the Company) which are intended to constitute Incentive Stock
Options shall not constitute Incentive Stock Options to the extent that such
options, in the aggregate, become exercisable for the first time in any one
calendar year for shares of Common Stock with an aggregate fair market value
(determined as of the respective date or dates of grant) of more than $100,000.

         (d)      TERMINATION OF EMPLOYMENT, DEATH OR DISABILITY. No Incentive
Stock Option may be exercised unless, at the time of such exercise, the optionee
is, and has been continuously since the date of grant of his or her option,
employed by the Company, except that:

                  (i)      an Incentive Stock Option may be exercised within the
         period of three months after the date the optionee ceases to be an
         employee of the Company (or within such lesser period as may be
         specified in the applicable option agreement), PROVIDED, that the
         agreement with respect to such option may designate a longer exercise
         period and that the exercise after such three-month period shall be
         treated as the exercise of a non-statutory option under the Plan;

                  (ii)     if the optionee dies while in the employ of the
         Company, or within three months after the optionee ceases to be such an
         employee, the Incentive Stock Option may be exercised by the person to
         whom it is transferred by will or the laws of descent and distribution
         within the period of



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         one year after the date of death (or within such lesser period as may
         be specified in the applicable option agreement); and

                  (iii)    if the optionee becomes disabled (within the meaning
         of Section 22(e)(3) of the Code or any successor provision thereto)
         while in the employ of the Company, the Incentive Stock Option may be
         exercised within the period of one year after the date the optionee
         ceases to be such an employee because of such disability (or within
         such lesser period as may be specified in the applicable option
         agreement).

For all purposes of the Plan and any option granted hereunder, "employment"
shall be defined in accordance with the provisions of Section 1.421-7(h) of the
Income Tax Regulations (or any successor regulations). Notwithstanding the
foregoing provisions, no Incentive Stock Option may be exercised after its
expiration date.

12.      ADDITIONAL PROVISIONS.

         (a)      ADDITIONAL OPTION PROVISIONS. The Board of Directors may, in
its sole discretion, include additional provisions in option agreements covering
options granted under the Plan, including without limitation restrictions on
transfer, repurchase rights, commitments to pay cash bonuses, to make, arrange
for or guaranty loans or to transfer other property to optionees upon exercise
of options, or such other provisions as shall be determined by the Board of
Directors; PROVIDED THAT such additional provisions shall not be inconsistent
with any other term or condition of the Plan and such additional provisions
shall not cause any Incentive Stock Option granted under the Plan to fail to
qualify as an Incentive Stock Option within the meaning of Section 422 of the
Code.

         (b)      ACCELERATION, EXTENSION, ETC. The Board of Directors may, in
its sole discretion, (i) accelerate the date or dates on which all or any
particular option or options granted under the Plan may be exercised or (ii)
extend the dates during which all, or any particular, option or options granted
under the Plan may be exercised.

13.      GENERAL RESTRICTIONS.

         (a)      INVESTMENT REPRESENTATIONS The Company may require any person
to whom an option is granted, as a condition of exercising such option, to give
written assurances in substance and form satisfactory to the Company to the
effect that such person is acquiring the Common Stock subject to the option for
his or her own account for investment and not with any present intention of
selling or otherwise distributing the same, and to such other effects as the
Company deems necessary or appropriate in order to comply with federal and
applicable state securities laws, or




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with covenants or representations made by the Company in connection with any
public offering of its Common Stock.

         (b)      COMPLIANCE WITH SECURITIES LAWS. Each option shall be subject
to the requirement that if, at any time, counsel to the Company shall determine
that the listing, registration or qualification of the shares subject to such
option upon any securities exchange or under any state or federal law, or the
consent or approval of any governmental or regulatory body, or that the
disclosure of non-public information or the satisfaction of any other condition
is necessary as a condition of, or in connection with, the issuance or purchase
of shares thereunder, such option may not be exercised, in whole or in part,
unless such listing, registration, qualification, consent or approval, or
satisfaction of such condition shall have been effected or obtained on
conditions acceptable to the Board of Directors. Nothing herein shall be deemed
to require the Company to apply for or to obtain such listing, registration or
qualification, or to satisfy such condition.

14. RIGHTS AS A STOCKHOLDER.

         The holder of an option shall have no rights as a stockholder with
respect to any shares covered by the option (including, without limitation, any
rights to receive dividends or non-cash distributions with respect to such
shares) until the date of issue of a stock certificate to him or her for such
shares. No adjustment shall be made for dividends or other rights for which the
record date is prior to the date such stock certificate is issued.

15.      ADJUSTMENT PROVISIONS FOR RECAPITALIZATIONS AND RELATED TRANSACTIONS.

         (a)      GENERAL. If, through or as a result of any merger,
consolidation, sale of all or substantially all of the assets of the Company,
reorganization, recapitalization, reclassification, stock dividend, stock split,
reverse stock split or other similar transaction, (i) the outstanding shares of
Common Stock are increased, decreased or exchanged for a different number or
kind of shares or other securities of the Company, or (ii) additional shares or
new or different shares or other securities of the Company or other non-cash
assets are distributed with respect to such shares of Common Stock or other
securities, an appropriate and proportionate adjustment may be made in (x) the
maximum number and kind of shares reserved for issuance under the Plan, (y) the
number and kind of shares or other securities subject to any then outstanding
options under the Plan, and (z) the price for each share subject to any then
outstanding options under the Plan, without changing the aggregate purchase
price as to which such options remain exercisable. Notwithstanding the
foregoing, no adjustment shall be made pursuant to this Section 15 if such
adjustment would cause the Plan to fail to comply with Section 422 of the Code.




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         (b)      BOARD AUTHORITY TO MAKE ADJUSTMENTS. Any adjustments under
this Section 15 will be made by the Board of Directors, whose determination as
to what adjustments, if any, will be made and the extent thereof will be final,
binding and conclusive. No fractional shares will be issued under the Plan on
account of any such adjustments.

16.      CHANGE OF CONTROL.

         Notwithstanding any other provision to the contrary in this Plan, in
the event of a Change of Control (as defined below), all options outstanding as
of the date such Change in Control occurs shall become exercisable in full,
whether or not exercisable in accordance with their terms. A "Change in Control"
shall occur or be deemed to have occurred only if any of the following events
occur: (i) any "person," as such term is used in Sections 13(d) and 14(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act") (other than the
Company, any trustee or other fiduciary holding securities under an employee
benefit plan of the Company, or any corporation owned directly or indirectly by
the stockholders of the Company in substantially the same proportion as their
ownership of stock of the Company) is or becomes the "beneficial owner" (as
defined in Rule 13d-3 under the Exchange Act), directly or indirectly, of
securities of the Company representing 50% or more of the combined voting power
of the Company's then outstanding securities; (ii) individuals who, as of the
date this Plan is adopted, constitute the Board of Directors of the Company (as
of the date thereof, the "Incumbent Board") cease for any reason to constitute
at least a majority of the Board, provided that any person becoming a director
subsequent to the date thereof whose election, or nomination for election by the
Company's stockholders, was approved by a vote of at least a majority of the
directors then comprising the Incumbent Board (other than an election or
nomination of an individual whose initial assumption of office is in connection
with an actual or threatened election contest relating to the election of the
directors of the Company, as such terms are used in Rule 14a-11 of Regulation
14A under the Exchange Act) shall be, for purposes of this Agreement, considered
as though such person were a member of the Incumbent Board; (iii) the
stockholders of the Company approve a merger or consolidation of the Company
with any other corporation, other than (A) a merger or consolidation which would
result in the voting securities of the Company outstanding immediately prior
thereto continuing to represent (either by remaining outstanding or by being
converted into voting securities of the surviving entity) more than 50% of the
combined voting power of the voting securities of the Company or such surviving
entity outstanding immediately after such merger or consolidation or (B) a
merger or consolidation effected to implement a recapitalization of the Company
(or similar transaction) in which no "person" (as hereinabove defined) acquires
more than 30% of the combined voting power of the Company's then outstanding
securities; or (iv) the stockholders of the Company approve a plan of complete
liquidation of the Company or an agreement for the sale or disposition by the
Company of all or substantially all of the Company's assets.



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17.      NO SPECIAL EMPLOYMENT RIGHTS.

         Nothing contained in the Plan or in any option shall confer upon any
optionee any right with respect to the continuation of his or her employment by
the Company or interfere in any way with the right of the Company at any time to
terminate such employment or to increase or decrease the compensation of the
optionee.

18.      OTHER EMPLOYEE BENEFITS.

         Except as to plans which by their terms include such amounts as
compensation, the amount of any compensation deemed to be received by an
employee as a result of the exercise of an option or the sale of shares received
upon such exercise will not constitute compensation with respect to which any
other employee benefits of such employee are determined, including, without
limitation, benefits under any bonus, pension, profit-sharing, life insurance or
salary continuation plan, except as otherwise specifically determined by the
Board of Directors.

19. AMENDMENT OF THE PLAN.

         (a)      The Board of Directors may at any time, and from time to time,
modify or amend the Plan in any respect, except that if at any time the approval
of the stockholders of the Company is required under Section 422 of the Code or
any successor provision with respect to Incentive Stock Options, or under Rule
16b-3, the Board of Directors may not effect such modification or amendment
without such approval.

         (b)      The termination or any modification or amendment of the Plan
shall not, without the consent of an optionee, affect his or her rights under an
option previously granted to him or her. With the consent of the optionee
affected, the Board of Directors may amend outstanding option agreements in a
manner not inconsistent with the Plan. The Board of Directors shall have the
right to amend or modify (i) the terms and provisions of the Plan and of any
outstanding Incentive Stock Options granted under the Plan to the extent
necessary to qualify any or all such options for such favorable federal income
tax treatment (including deferral of taxation upon exercise) as may be afforded
incentive stock options under Section 422 of the Code and (ii) the terms and
provisions of the Plan and of any outstanding option to the extent necessary to
ensure the qualification of the Plan under Rule 16b-3.

20.      WITHHOLDING.

         (a)      The Company shall have the right to deduct from payments of
any kind otherwise due to the optionee any federal, state or local taxes of any
kind required by



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law to be withheld with respect to any shares issued upon exercise of options
under the Plan. Subject to the prior approval of the Company, which may be
withheld by the Company in its sole discretion, the optionee may elect to
satisfy such obligations, in whole or in part, (i) by causing the Company to
withhold shares of Common Stock otherwise issuable pursuant to the exercise of
an option or (ii) by delivering to the Company shares of Common Stock already
owned by the optionee. The shares so delivered or withheld shall have a fair
market value equal to such withholding obligation. The fair market value of the
shares used to satisfy such withholding obligation shall be determined by the
Company as of the date that the amount of tax to be withheld is to be
determined. An optionee who has made an election pursuant to this Section 20(a)
may only satisfy his or her withholding obligation with shares of Common Stock
which are not subject to any repurchase, forfeiture, unfulfilled vesting or
other similar requirements.

         (b)      Notwithstanding the foregoing, in the case of a Reporting
Person, no election to use shares for the payment of withholding taxes shall be
effective unless made in compliance with any applicable requirements of Rule
16b-3 (unless it is intended that the transaction not qualify for exemption
under Rule 16b-3).

21.      CANCELLATION AND NEW GRANT OF OPTIONS, ETC.

         The Board of Directors shall have the authority to effect, at any time
and from time to time, with the consent of the affected optionees, (i) the
cancellation of any or all outstanding options under the Plan and the grant in
substitution therefor of new options under the Plan covering the same or
different numbers of shares of Common Stock and having an option exercise price
per share which may be lower or higher than the exercise price per share of the
cancelled options or (ii) the amendment of the terms of any and all outstanding
options under the Plan to provide an option exercise price per share which is
higher or lower than the then-current exercise price per share of such
outstanding options.

22.      EFFECTIVE DATE AND DURATION OF THE PLAN.

         (a)      EFFECTIVE DATE. The Plan shall become effective when adopted
by the Board of Directors, but no option granted under the Plan shall become
exercisable unless and until the Plan shall have been approved by the Company's
stockholders. If such stockholder approval is not obtained within twelve months
after the date of the Board's adoption of the Plan, options previously granted
under the Plan shall not vest and shall terminate and no options shall be
granted thereafter. Amendments to the Plan not requiring stockholder approval
shall become effective when adopted by the Board of Directors; amendments
requiring stockholder approval (as provided in Section 19) shall become
effective when adopted by the Board of Directors, but no option granted after
the date of such amendment shall become exercisable (to the extent that such
amendment to the Plan was required to grant such option to a



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particular person) unless and until such amendment shall have been approved by
the Company's stockholders. If such stockholder approval is not obtained within
twelve months of the Board's adoption of such amendment, any options granted on
or after the date of such amendment shall terminate to the extent that such
amendment was required to enable the Company to grant such option to a
particular optionee. Subject to this limitation, options may be granted under
the Plan at any time after the effective date and before the date fixed for
termination of the Plan.

         (b)      TERMINATION. Unless sooner terminated in accordance with
Section 16 herein, the Plan shall terminate upon the close of business on the
day next preceding the tenth anniversary of the date of its adoption by the
Board of Directors. Options outstanding on such date shall continue to have
force and effect in accordance with the provisions of the instruments evidencing
such options.

23.      PROVISION FOR FOREIGN PARTICIPANTS.

         The Board of Directors may, without amending the Plan, modify awards or
options granted to participants who are foreign nationals or employed outside
the United States to recognize differences in laws, rules, regulations or
customs of such foreign jurisdictions with respect to tax, securities, currency,
employee benefit or other matters.



                                     Adopted by the Board of Directors on
                                     May 30, 1995


                                     Adopted by the Stockholders of the Company
                                     on July 21, 1995









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