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                                                                 EXHIBIT 10.18

                              BELCO OIL & GAS CORP.

                      RETENTION AND SEVERANCE BENEFIT PLAN

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                              BELCO OIL & GAS CORP.
                      RETENTION AND SEVERANCE BENEFIT PLAN

                                   ARTICLE I.
                                   DEFINITIONS

         1.1 "AGREEMENT" means the Agreement and Plan of Merger between Westport
Resources Corporation and the Company.

         1.2 "AGREEMENT EXECUTION DATE" means the date the Agreement is executed
by the Company and Westport Resources Corporation.

         1.3 "CAUSE" means, in the context of an Employee's termination or
separation from employment with the Company, an Employee's (i) neglect, refusal
or failure (other than by reason of illness, accident or other physical or
mental incapacity or disability) to properly or substantially attend to duties
as assigned by the Company; (ii) failure to substantially comply with any of
terms of employment; (iii) failure to follow the established policies,
standards, and regulations of the Company; (iv) willful engagement in gross
misconduct injurious to the Company or to any of its subsidiaries or affiliates
or any of its or their employees; or (v) conviction in a court of law of, or
pleading of guilty or nolo contendere to, any crime that constitutes a felony in
the jurisdiction involved, or any crime including moral turpitude.

         1.4 "CODE" means the Internal Revenue Code of 1986, as amended.

         1.5 "COMPANY" means Belco Oil & Gas Corp., and any successors thereto.

         1.6 "EFFECTIVE DATE" means the Agreement Execution Date.

         1.7 "EMPLOYEE" means any individual who is employed by the Company or
any entity included with the Company in a controlled group of corporations or
trades or businesses under common control within the meaning of sections 414(b)
or 414(c) of the Code, or an affiliated service group within the meaning of
section 414(m) of the Code.

         1.8 "ERISA" means the Employee Retirement Income Security Act of 1974,
as amended.

         1.9 "PLAN" means the Belco Oil & Gas Retention and Severance Benefit
Plan, as amended from time to time.

         1.10 "PLAN ADMINISTRATOR" means the Company or an individual or
committee it may designate.

         1.11 "RETENTION-ELIGIBLE EMPLOYEE" means each full-time or part-time
Employee who is employed by the Company on the Agreement Execution Date.
Employees classified as temporary employees by the Company and individuals who
are classified as independent contractors are not Retention-Eligible Employees.

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         1.12 "RETENTION PERIOD" means the period from the Agreement Execution
Date to the earliest of (i) 90 days after the Closing Date, as defined in the
Agreement, (ii) termination of the Agreement, and (iii) an employee's notice of
termination.

         1.13 "SEVERANCE-ELIGIBLE EMPLOYEE" means each full-time or part-time
Employee. Employees classified as temporary employees by the Company and
individuals who are classified as independent contractors are not
Severance-Eligible Employees.

         1.14 "SEVERANCE PERIOD" means the period from the Agreement Execution
Date to the earlier of (i) eighteen months after the Closing Date, as defined in
the Agreement and (ii) termination of the Agreement.

                                  ARTICLE II.
                                RETENTION BENEFIT

         2.1 AMOUNT OF BENEFIT. Each Retention-Eligible Employee shall receive a
payment of 30% of such Retention-Eligible Employee's salary earned during the
Retention Period. For purposes of this Article II, salary means, for salaried
employees, base salary and shall not include any bonuses, overtime, incentive
compensation, or similar types of wages; and for hourly employees, the average
number of hours worked per week over the twelve-month period ending on the
earlier of the Employee's termination date or the end of the Retention Period,
but not more than forty (40) hours per week, times the Employee's most recent
hourly wage in effect at the time a retention benefit becomes payable under this
Plan.

         2.2 VOLUNTARY TERMINATION. Notwithstanding any other provision in the
Plan to the contrary, a Retention-Eligible Employee who voluntarily terminates
employment during the Retention Period shall receive no retention benefits under
the Plan, unless such voluntary termination is a result of a material change in
compensation or a requirement to relocate principal place of employment by more
than 25 miles.

         2.3 TERMINATION FOR CAUSE. The Plan Administrator shall determine
whether a Retention-Eligible Employee has been terminated for Cause. If the Plan
Administrator reasonably determines that a Retention-Eligible Employee has been
terminated for Cause, the Retention-Eligible Employee shall receive no retention
benefits under the Plan.

         2.4 FORM AND TIMING OF PAYMENT. The payment made under this Article II
shall be paid as a lump sum within 30 days after the end of the Retention
Period.

         2.5 TREATMENT OF PAYMENT UNDER 401(K) PLAN. This lump sum payment shall
be deemed a "performance bonus" for purposes of the Belco Oil & Gas Employee
401(k) Savings Plan, and shall not be eligible to be deferred.

                                  ARTICLE III.
                               SEVERANCE BENEFITS

         3.1 AMOUNT OF BENEFIT. A Severance-Eligible Employee whose employment
is terminated without Cause by the Company during the Severance Period shall be
entitled to severance benefits under this Plan according to the following
schedule:

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<TABLE>
<CAPTION>
POSITION                                       SEVERANCE FORMULA                                    MAXIMUM BENEFIT
--------                                       -----------------                                    ---------------
<S>                                            <C>                                                  <C>
Senior Vice President and above                Three months salary per year of service              18 months salary

Vice President                                 Two months salary per year of service                12 months salary

All others                                     One months salary per year of service                 6 months salary
</TABLE>

The minimum severance benefit shall be two months salary. The benefit shall be
pro-rated for partial years of service. Years of service shall include service
with the Company as well as service with Belco Operating Corp., Coda Energy,
Inc. and Taurus Energy Corp., provided, however, that no credit shall be given
under this Plan for any industry service with any other entities. For purposes
of this Article III, salary means, for salaried employees, base salary and shall
not include any bonuses, overtime, incentive compensation, or similar types of
wages; and for hourly employees, the average number of hours worked per week
over the twelve-month period ending on the Employee's termination date, but not
more than forty (40) hours per week, times the Employee's most recent hourly
wage in effect at the time a severance benefit becomes payable under this Plan.

         3.2 VOLUNTARY TERMINATION. Notwithstanding any other provision in the
Plan to the contrary, a Severance-Eligible Employee who voluntarily terminates
employment with the Company shall receive no severance benefits under the Plan,
unless such voluntary termination is a result of a material change in
compensation or a requirement to relocate principal place of employment by more
than 25 miles.

         3.3 TERMINATION FOR CAUSE. The Plan Administrator shall determine
whether a Severance-Eligible Employee has been terminated for Cause. If the Plan
Administrator reasonably determines that a Severance-Eligible Employee has been
terminated for Cause, the Severance-Eligible Employee shall receive no severance
benefits under the Plan.

         3.4 FORM AND TIMING OF PAYMENT. Each Severance-Eligible Employee
entitled to a benefit under this Article III may elect to receive either (i) a
lump-sum payment, paid within 30 days from the date such Severance-Eligible
Employee's employment is terminated, or (ii) equal periodic payments, made on
normal payroll schedule, for the number of months for which the
Severance-Eligible Employee is entitled to payment.

         3.5 RELEASE REQUIREMENT. Payment of benefits under this Section III are
conditioned upon the execution of a release, in a form satisfactory to the
Company, of employment-related claims.

         3.6 MEDICAL BENEFITS. Severance-Eligible Employees who elect to receive
monthly payments under Section 3.4(ii) shall, for the period over which payments
are made, be entitled to receive continuation coverage under the Consolidated
Omnibus Budget Reconciliation Act ("COBRA coverage") by paying the current
active employee rate (i.e., the rate in effect at the time post-termination
premium payments are deducted) for plans under which the Severance-Eligible
Employee had participated prior to termination, such amounts to be deducted by
the Company on an after-tax basis from the Severance-Eligible Employee's
periodic payments. After severance payments cease, Severance-Eligible Employees
shall be entitled to continue

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COBRA coverage for the rest of the period permitted by COBRA by paying the full
COBRA rate.

         3.7 MAXIMUM BENEFIT. Notwithstanding any provision in the Plan to the
contrary, unless otherwise determined by the Plan Administrator, no amounts
shall be payable under the Plan which, when combined with any other payments to
the Severance-Eligible Employee, would not be deductible by the Company under
Section 280G of the Code or would subject the Severance-Eligible Employee to
taxation under Section 4999 of the Code.

         3.8 TREATMENT OF PAYMENT UNDER 401(K) PLAN. Severance benefit payments
are not eligible for deferrals under the Belco Oil & Gas Employee 401(k) Savings
Plan.

                                  ARTICLE IV.
                               GENERAL PROVISIONS

         4.1 FUNDING AND COST OF PLAN. The benefits provided herein shall be
unfunded and shall be provided from the Company's general assets. The cost of
providing benefits under the Plan shall be borne by the Company.

         4.2 NAMED FIDUCIARY. The Plan Administrator shall be the named
fiduciary for purposes of ERISA.

         4.3 ADMINISTRATION. The Plan Administrator shall be responsible for the
management and control of the operation and the administration of the Plan,
including without limitation, interpretation of the Plan, decisions pertaining
to eligibility to participate in the Plan, computation of Plan benefits,
granting or denial of benefit claims, and review of claims denials. The Plan
Administrator has absolute discretion in the exercise of its powers and
responsibilities. The Company may delegate any or all of its powers and
responsibilities as Plan Administrator to an individual, a committee, or both.
To the extent the Company delegates its responsibilities and powers as Plan
Administrator, the Company shall, without limiting any rights that the delegate
may have under the Company's charter or bylaws, applicable law or otherwise,
indemnify and hold harmless each such delegate (and any other individual acting
on such delegate's behalf) against any and all expenses and liabilities arising
out of such person's administrative functions or fiduciary responsibilities,
excepting only expenses and liabilities arising out of the person's own gross
negligence or willful misconduct (but specifically including such person's
ordinary negligence); expenses against which such person shall be indemnified
hereunder include without limitation the amounts of any settlement, judgment,
attorneys' fees, costs of court, and any other related charges reasonably
incurred in connection with a claim, proceeding, settlement, or other action
under the Plan.

         4.4 PLAN YEAR. The Plan shall be administered on a calendar year basis.

         4.5 AMENDMENT AND TERMINATION. For a period of three years from the
Effective Date, the Company may not amend or terminate the Plan in any manner
that would adversely affect the benefits provided under Articles II and III.

         4.6 CLAIMS PROCEDURE AND REVIEW. Claims for benefits under the Plan
shall be made in writing to the Plan Administrator. If a claim for benefits is
wholly or partially denied,

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the Plan Administrator shall, within a reasonable period of time but no later
than 90 days after receipt of the claim (or 180 days after receipt of the claim
if special circumstances require an extension of time for processing the claim),
notify the claimant of the denial. Such notice shall (i) be in writing, (ii) be
written in a manner calculated to be understood by the claimant, (iii) contain
the specific reason or reasons for denial of the claim, (iv) refer specifically
to the pertinent Plan provisions upon which the denial is based, (v) describe
any additional material or information necessary for the claimant to perfect the
claim (and explain why such material or information is necessary), and (vi)
explain the Plan's claim review procedure. Within 60 days of the receipt by the
claimant of this notice, the claimant may file a written appeal with the Plan
Administrator. In connection with the appeal, the claimant may review Plan
documents and may submit written issues and comments. The Plan Administrator
shall deliver to the claimant a written decision on the appeal promptly, but not
later than 60 days after the receipt of the claimant's appeal (or 120 days after
receipt of the claimant's appeal if there are special circumstances which
require an extension of time for processing). Such decision shall (i) be written
in a manner calculated to be understood by the claimant, (ii) include specific
reasons for the decision, and (iii) refer specifically to the Plan provisions
upon which the decision is based. If special circumstances require an extension,
up to 180 or 120 days, whichever applies, the Plan Administrator shall send
written notice of the extension. This notice shall indicate the special
circumstances requiring the extension and state when the Plan Administrator
expects to render the decision.

         4.7 NOT CONTRACT OF EMPLOYMENT. The adoption and maintenance of the
Plan shall not be deemed to be a contract of employment between the Company and
any person, to be consideration for the employment of any person, or to have any
effect whatsoever on the at-will employment relationship. Nothing in the Plan
shall be deemed to give any person the right to be retained in the employ of the
Company or to restrict the right of the Company to change compensation, change
employment duties or discharge any person at any time. Nothing in the Plan shall
be deemed to give the Company the right to require any person to remain in the
employ of such Company or to restrict any person's right to terminate employment
at any time.

         4.8 GOVERNING LAW. This Plan shall be interpreted under the laws of the
State of Texas except to the extent preempted by federal law.

         4.9 GENDER; NUMBER. Wherever appropriate herein, the masculine, neuter,
and feminine genders shall be deemed to include each other, and the plural shall
be deemed to include the singular and vice versa.

         4.10 OVERPAYMENT. If, due to mistake or any other reason, a person
receives benefits under this Plan in excess of what the Plan provides, that
person shall repay the overpayment to the Company in a lump sum within thirty
days of notice of the amount of overpayment. If that person fails to so repay
the overpayment, then without limiting any other remedies available to the
Company, the Company may deduct the amount of the overpayment from any other
amounts which become payable to that person under the Plan or otherwise.

         4.11 HEADINGS. The headings of the Articles and Sections are included
solely for convenience. If the headings and the text of the Plan conflict, the
text shall control. All references to Articles and Sections are to the Plan
unless otherwise indicated.

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         4.12 SEVERABILITY. If any provision of the Plan is held to be illegal
or invalid for any reason, that holding shall not affect the remaining
provisions of the Plan. Instead, the Plan shall be construed and enforced as if
such illegal or invalid provision had not been contained herein.

         4.13 MITIGATION. A Severance-Eligible Employee or a Retention-Eligible
Employee will not be required to mitigate the amount of any payment required
hereunder unless otherwise determined by the Plan Administrator.

         4.14 WITHHOLDING. The Company may withhold from any amounts payable
under the Plan any federal, state or local taxes as the Company is required to
withhold pursuant to any law or government regulation or ruling.

         IN WITNESS WHEREOF, Belco Oil & Gas Corp. has executed the Belco Oil &
Gas Corp. Retention and Severance Benefit Plan this 8th day of June, 2001.

                                          BELCO OIL & GAS CORP.

                                          By: /s/ GRANT W. HENDERSON
                                              ---------------------------------
                                          Name: Grant W. Henderson
                                                -------------------------------
                                          Title: President & CEO
                                                 ------------------------------

                                       6<PAGE>   1
                                                                   Exhibit 10.14

                            MCK COMMUNICATIONS, INC.

                      NON-QUALIFIED STOCK OPTION AGREEMENT

Name of Optionee:             Glenda Davis

No. of Option Shares:         500,000 Shares of Common Stock

Vesting Commencement Date:    January 19, 2001

Grant Date:                   March 13, 2001

Option Exercise Price/Share:  $2.5312

     MCK Communications, Inc. a Delaware corporation (together with all
successors thereto, the "COMPANY"), hereby grants to the person named above (the
"OPTIONEE"), who is an officer, employee, director, Consultant or other key
person of the Company or any of its Subsidiaries (as defined below), an option
(the "STOCK OPTION") to purchase on or prior to the Expiration Date (as defined
in Section 1(c) below), all or any part of the number of shares of Common Stock,
par value $.001 per share ("COMMON STOCK"), of the Company indicated above (the
"OPTION SHARES," and such shares once issued shall be referred to as the "ISSUED
SHARES"), at the option exercise price per share specified above (the "OPTION
EXERCISE PRICE"), subject to the terms and conditions set forth in this
Non-Qualified Stock Option Agreement (the "AGREEMENT"). This Stock Option is NOT
intended to qualify as an "incentive stock option" as defined in Section 422(b)
of the Internal Revenue Code of 1986, as amended from time to time (the "CODE").

     For purposes of this Agreement, the following terms shall have the
following respective meanings:

     "CAUSE" shall mean the determination by a majority of the Board of
Directors of the Company that are not employees of the Company that any one or
more of the following events has occurred: (A) dishonesty, breach of fiduciary
duty or breach of the terms of this Agreement or any other agreements executed
by the Optionee; (B) commission by the Optionee of any act of embezzlement,
fraud, larceny or theft on or from the Company; (C) substantial and continuing
neglect or inattention by the Optionee of duties of his employment which shall
continue for 30 business days following written notification by the Board of
Directors; (D) willful misconduct or gross negligence of the Optionee in
connection with the performance of such duties; (E) commission by the Optionee
of any acts of moral turpitude; (F) the conviction of the Optionee of a felony.
A determination by the Board of Directors, after notice to the Optionee and
providing the Optionee an opportunity to be heard, that the Optionee has
committed an act of the sort mentioned in (A) through (F) above shall be
conclusive, whether or not there are proceedings by public authorities with
respect thereto and without regard to the outcome thereof.

     "CONSULTANT" means a person engaged to provide consulting or advisory
services (other than as an employee or director) to the Company or its
Subsidiaries, provided that the identity of such person, the nature of such
services or the entity to which such services are provided would not preclude
the Company from offering or selling securities to such person

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pursuant to the Plan in reliance on registration on a Form S-8 Registration
Statement under the Act.

          "FAIR MARKET VALUE" means the closing price reported for the Stock on
the NASDAQ National Market System for such date or, if no sales were reported
for such date, for the last date preceding such date for which a sale was
reported.

          "GOOD REASON" shall mean the occurrence of any of the following
events: (i) a substantial adverse change in the nature or scope of the Grantee's
responsibilities, authorities, powers, functions or duties (other than changes
to reflect an integration of the Company into an acquiring entity in the event
of a Corporate Transaction); or (ii) a reduction in the Grantee's annual base
salary or bonus compensation (subject to applicable performance requirements
with respect to the actual amount of bonus compensation earned) except for
across-the-board reductions similarly affecting all, or substantially all,
similar employees.

          "SERVICE RELATIONSHIP" the Grantee's employment or service with the
Company or its Subsidiaries, whether in the capacity of an employee, director or
a Consultant. Unless otherwise determined by the Board of Directors, the
Grantee's Service Relationship shall not be deemed to have terminated merely
because of a change in the capacity in which the Optionee renders service to the
Company or a transfer between locations of the Company or its Subsidiaries or a
transfer between the Company and any Subsidiary, provided that there is no
interruption or other termination of the Service Relationship. The Board of
Directors, in its discretion, shall determine whether the Grantee's Service
Relationship has terminated and the effective date of such termination.

          "SUBSIDIARY" means any corporation or other entity (other than the
Company) in any unbroken chain of corporations or other entities, beginning with
the Company, if each of the corporations or entities (other than the last
corporation or entity in the unbroken chain) owns stock or other interests
possessing 50% or more of the economic interest or the total combined voting
power of all classes of stock or other interests in one of the other
corporations or entities in the chain.

     1.   VESTING, EXERCISABILITY, AND TERMINATION.

          (a) This Stock Option shall be vested with respect to 25% of the
Option Shares on the first anniversary of the Vesting Commencement Date, and
2.083% of the Option Shares on each monthly anniversary of the Vesting
Commencement Date thereafter (the "VESTED SHARES"), such that all of the Option
Shares shall be Vested Shares on January 19, 2005. The term "UNVESTED SHARES"
shall mean any shares of Common Stock that are not Vested Shares.
Notwithstanding the foregoing, this Stock Option shall be subject to accelerated
vesting upon the occurrence of a Corporate Transaction (as defined in Section 5
below).

          (b) Except as set forth in Section 5, in the event that the Optionee's
Service Relationship (as defined below) with the Company and its Subsidiaries
terminates for any reason or under any circumstances, including the Optionee's
resignation, retirement or termination by the Company, upon the Optionee's death
or disability, or for any other reason, regardless of the

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circumstances thereof, this Stock Option may thereafter be exercised, to the
extent it was vested and exercisable on such date of such termination, until the
date specified in Section 1(c) below. Any portion of the Stock Option that is
not vested and exercisable on the date of termination of the Optionee's Service
Relationship with the Company shall immediately expire and be null and void.

          (c) Subject to the provisions of Section 5 below, once any portion of
this Stock Option becomes exercisable, it shall continue to be exercisable by
the Optionee or her successors as contemplated herein at any time or times prior
to the earliest of (i) the date which is (A) 12 months following the date on
which the Optionee's Service Relationship with the Company and its Subsidiaries
terminates due to death or disability (as defined in Section 422(c)(6) of the
Code) or (B) 90 days following the date on which the Optionee's Service
Relationship with the Company terminates if the termination is due to any other
reason, provided however, if the Optionee's Service Relationship with the
Company is terminated for Cause, this Stock Option shall terminate immediately
upon the date of the Optionee's termination, or (ii) the date ten (10) years
from the Grant Date (the earlier to occur of such dates being the "EXPIRATION
DATE"). For purposes of this Agreement the Compensation Committee of the Board
of Directors of the Company or the Board of Directors of the Company, as
applicable (the "COMMITTEE"), shall have sole discretion to determine the reason
for the termination of the Optionee's Service Relationship with the Company or
any Subsidiary.

     2.   EXERCISE OF STOCK OPTION.

          (a) The Optionee may exercise this Stock Option only in the following
manner: Prior to the Expiration Date (subject to Sections 1(c) and 5), the
Optionee may deliver a Stock Option exercise notice (an "EXERCISE NOTICE") in
the form of APPENDIX A hereto indicating his or her election to purchase some or
all of the Option Shares specifying the number of Option Shares to be purchased
and identifying which shares are Vested Shares and which shares are Unvested
Shares. Payment of the purchase price may be made by one or more of the
following methods:

               (i) In cash by certified or bank check or other instrument
acceptable to the Committee; or

               (ii) In the form of shares of Common Stock that are not then
subject to restrictions under any Company plan and that have been held by the
Optionee free of such restrictions for at least six months, if permitted by the
Committee in its discretion, such surrendered shares shall be valued at Fair
Market Value on the exercise date;

               (iii) By the Optionee delivering to the Company a properly
executed exercise notice together with irrevocable instructions to a broker to
promptly deliver to the Company cash or a check payable and acceptable to the
Company to pay the purchase price; PROVIDED that, in the event the Optionee
chooses to pay the purchase price as so provided, the Optionee and the broker
shall comply with such procedures and enter into such agreements of indemnity
and other agreements as the Committee shall prescribe as a condition of such
payment procedure;

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               (iv) By the Optionee delivering to the Company a promissory note
if the Board has authorized the loan of funds to the Optionee for the purpose of
enabling or assisting the Optionee to effect the exercise of her Stock Option;
PROVIDED THAT at least so much of the exercise price as represents the par value
of the Stock shall be paid other than with a promissory note.

          (b) Certificates for the Option Shares so purchased will be issued and
delivered to the Optionee upon compliance to the satisfaction of the Committee
with all requirements under applicable laws or regulations in connection with
such issuance. Until the Optionee shall have complied with the requirements
hereof, the Company shall be under no obligation to issue the Option Shares
subject to this Stock Option, and the determination of the Committee as to such
compliance shall be final and binding on the Optionee. The Optionee shall not be
deemed to be the holder of, or to have any of the rights of a holder with
respect to, any shares of stock subject to this Stock Option unless and until
this Stock Option shall have been exercised pursuant to the terms hereof, the
Company shall have issued and delivered the Option Shares to the Optionee, and
the Optionee's name shall have been entered as a stockholder of record on the
books of the Company. Thereupon, the Optionee shall have full dividend and other
ownership rights with respect to such Issued Shares, subject to the terms of
this Agreement.

          (c) Notwithstanding any other provision hereof, no portion of this
Stock Option shall be exercisable after the Expiration Date, including such date
as is contemplated by Section 5 hereof.

     3.   TRANSFERABILITY. This Option is personal to the Optionee and is not
transferable by the Optionee in any manner other than by will or by the laws of
descent and distribution; provided that this Stock Option may be transferred by
the Optionee without consideration for the transfer, to members of the
Optionee's immediate family, to trusts for the benefit of such family members,
or to partnerships in which such family members are the only partners, or to
limited liability companies in which such family members are the only members
(each a "PERMITTED TRANSFEREE"), PROVIDED that the transferee agrees in writing
with the Company to be bound by all of the terms and conditions of this Option
Agreement. This Option may be exercised during the Optionee's lifetime only by
the Optionee (or by the Optionee's legal representative or guardian in the event
of the Optionee's incapacity) or by a Permitted Transferee pursuant to this
Section 3. The Optionee may elect to designate a beneficiary by providing
written notice of the name of such beneficiary to the Company, and may revoke or
change such designation at any time by filing written notice of revocation or
change with the Company; such beneficiary may exercise the Optionee's Option in
the event of the Optionee's death to the extent provided herein. If the Optionee
does not designate a beneficiary, or if the designated beneficiary predeceases
the Optionee, the executor of the Optionee may exercise this Option to the
extent provided herein in the event of the Grantee's death.

     4.   ADJUSTMENT UPON CHANGES IN CAPITALIZATION. The shares of stock covered
by this Stock Option are shares of Common Stock of the Company. Subject to
Section 5 hereof, if the shares of Common Stock as a whole are increased,
decreased, changed or converted into or exchanged for a different number or kind
of shares or securities of the Company or any successor entity (or a parent or
Subsidiary thereof), whether through merger or consolidation, sale of all or
substantially all of the assets of the Company, reorganization,
recapitalization, reclassification, stock dividend, stock split, combination of
shares, exchange of shares, change in corporate

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structure or the like, an appropriate and proportionate adjustment shall be made
in the number and kind of shares and in the per share exercise price of shares
subject to any unexercised portion of this Stock Option. In the event of any
such adjustment in this Stock Option, the Optionee thereafter shall have the
right, subject to Section 5, to purchase the number of shares under this Stock
Option at the per share price, as so adjusted, which the Optionee could purchase
at the total purchase price applicable to this Stock Option immediately prior to
such adjustment, all references herein to Common Stock shall be deemed to refer
to the security that is subject to acquisition upon exercise of this Stock
Option and all references to the Company shall be deemed to refer to the issuer
of such security. Adjustments under this Section 4 shall be determined by the
Committee, whose determination as to what adjustment shall be made, and the
extent thereof, shall be conclusive. No fractional shares of Common Stock shall
be issued resulting from any such adjustment, but the Company in its discretion
may make a cash payment in lieu of fractional shares.

     5.   EFFECT OF CORPORATE TRANSACTIONS. In the case of (i) a merger,
reorganization or consolidation between the Company and another person or entity
(other than a holding company or Subsidiary of the Company) as a result of which
the holders of the Company's outstanding voting stock immediately prior to the
transaction hold less than a majority of the outstanding voting stock of the
surviving entity immediately after the transaction, (ii) the sale of all or
substantially all of the assets of the Company to an unrelated person or entity,
or (iii) the direct or indirect sale or exchange in a single or series of
related transactions by the stockholders of the Company of more than fifty
percent (50%) of all of the Common Stock of the Company to an unrelated person
or entity as a result of which the holders of the Company's outstanding voting
stock immediately prior to the transaction hold less than a majority of the
outstanding voting stock of the surviving entity immediately after the
transaction (in each case, a "CORPORATE TRANSACTION"), upon the effectiveness of
the Corporate Transaction, unless provision is made in connection with the
Corporate Transaction for the assumption of this Stock Option, or the
substitution of this Stock Option with a new stock option of the successor
entity or parent thereof (the "ASSUMPTION"), one hundred percent (100%) of the
remaining Unvested Shares subject to this Stock Option shall, subject to and
conditioned upon the effectiveness of the Corporate Transaction, become Vested
Shares fifteen (15) days prior to the anticipated effective date of the
Corporate Transaction as determined by the Committee. Further, unless there is
an Assumption, this Stock Option shall terminate upon the effectiveness of the
Corporate Transaction. In the event of such termination, the Optionee shall be
permitted to exercise this Option for a period of at least fifteen (15) days
prior to the anticipated effective date of such Corporate Transaction, to the
extent that it is then vested and exercisable (after giving effect to the
acceleration of vesting provided for in this Section 5, PROVIDED, HOWEVER, that
(i) the exercise of the portion of this Stock Option that becomes vested and
exercisable pursuant to the acceleration provisions of this Section 5, shall be
subject to and conditioned upon the effectiveness of the Corporate Transaction;
and (ii) the Optionee may, but will not be required to, condition the exercise
of any portion of this Stock Option not described in (i) above upon the
effectiveness of the Corporate Transaction. If there is an Assumption, the
remaining Option Shares subject to this Stock Option shall continue to vest in
accordance with the percentage set forth herein; PROVIDED, THAT if the
Optionee's Service Relationship with such successor entity or parent thereof is,
on or within twelve (12) months after such Corporate Transaction, terminated by
such successor entity or parent thereof without Cause or terminated by the
Optionee for Good Reason then the remaining Unvested Shares subject to this
Stock Option shall become Vested Shares.

                                      -5-
<PAGE>   6

     6.   UNVESTED SHARE REPURCHASE OPTION.

          (a) GRANT OF UNVESTED SHARE REPURCHASE OPTION. If the Optionee's
Service Relationship is terminated for any reason or no reason, with or without
cause, or if the Optionee, the Optionee's legal representative or other holder
of Issued Shares attempts to sell exchange, transfer, pledge, or otherwise
dispose of (other than pursuant to a Corporate Transaction) any Unvested Shares,
the Company shall have the right to repurchase the Unvested Shares under the
terms and subject to the conditions set forth in this Section 7 (the "UNVESTED
SHARE REPURCHASE OPTION").

          (b) EXERCISE OF UNVESTED SHARE REPURCHASE OPTION. The Company may
exercise the Unvested Share Repurchase Option by written notice to the Optionee
within sixty (60) days after (a) termination of the Optionee's Service
Relationship (or exercise of this Stock Option, if later) or (b) the Company has
received notice of the attempted disposition of Unvested Shares. If the Company
fails to give notice within such sixty (60) day period, the Unvested Share
Repurchase Option shall terminate unless the Company and the Optionee have
extended the time for the exercise of the Unvested Share Repurchase Option. The
Unvested Share Repurchase Option may be exercised for any or all of the Unvested
Shares.

          (c) PAYMENT FOR SHARES AND RETURN OF SHARES TO COMPANY. The purchase
price per share being repurchased by the Company shall be an amount equal to the
Optionee's original cost per share, as adjusted pursuant to Section 4 (the
"REPURCHASE PRICE"). The Company shall pay the aggregate Repurchase Price to the
Optionee in cash within thirty (30) days after the date of the written notice to
the Optionee of the Company's exercise of the Unvested Share Repurchase Option.
For purposes of the foregoing, cancellation of any purchase money indebtedness
of the Optionee to the Company for the shares shall be treated as payment to the
Optionee in cash to the extent of the unpaid principal and any accrued interest
canceled. The shares being repurchased shall be delivered to the Company by the
Optionee at the same time as the delivery of the Repurchase Price to the
Optionee.

          (d) ASSIGNMENT OF UNVESTED SHARE REPURCHASE OPTION. The Company shall
have the right to assign the Unvested Share Repurchase Option at any time,
whether or not such option is then exercisable, to one or more persons as may be
selected by the Company.

     7.   ELECTION UNDER SECTION 83(b) OF THE CODE. If the Optionee exercises
this Stock Option prior to vesting (or at a time when this Stock Option is
otherwise nontransferable and subject to a substantial risk of forfeiture), the
Optionee understands that the Optionee should consult with the Optionee's tax
advisor regarding the advisability of filing with the Internal Revenue Service
and election under Section 83(b) of the Code. This election must be filed no
later than thirty (30) days after the date on which the Optionee exercises this
Stock Option for Unvested Shares. Failure to file an election under Section
83(b), if appropriate, may result in adverse tax consequences to the Optionee.
The Optionee acknowledges that the Optionee has been advised to consult with a
tax advisor prior to the exercise of the Option regarding the tax consequences
to the Optionee of the exercise of this Stock Option. AN ELECTION UNDER SECTION
83(b) MUST BE FILED WITHIN 30 DAYS AFTER THE DATE OF WHICH THE OPTIONEE
PURCHASES UNVESTED SHARES. THIS TIME PERIOD CANNOT BE EXTENDED. THE OPTIONEE
ACKNOWLEDGES THAT TIMELY FILING OF A SECTION 83(b) ELECTION IS THE OPTIONEE'S
SOLE RESPONSIBILITY, EVEN IF THE

                                      -6-
<PAGE>   7

OPTIONEE REQUESTS THE COMPANY OR ITS REPRESENTATIVE TO FILE SUCH ELECTION ON HIS
OR HER BEHALF.

     8.   LEGENDS. The Company may at any time place legends referencing the
Unvested Share Repurchase Option, on all certificates representing shares of
stock subject to the provisions of this Agreement. The Optionee shall, at the
request of the Company, promptly present to the Company any and all certificates
representing shares acquired pursuant to this Stock Option in the possession of
the Optionee in order to carry out the provisions of this Section. Unless
otherwise specified by the Company, legends placed on such certificates may
include, but shall not be limited to, the following:

          "THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO AN UNVESTED
SHARE REPURCHASE OPTION IN FAVOR OF THE CORPORATION OR ITS ASSIGNEE SET FORTH IN
AN AGREEMENT BETWEEN THE CORPORATION AND THE REGISTERED HOLDER, OR SUCH HOLDER'S
PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT THE PRINCIPAL OFFICE OF
THIS CORPORATION."

     9.   WITHHOLDING TAXES. The Optionee shall, not later than the date as of
which the exercise of this Stock Option becomes a taxable event for federal
income tax purposes, pay to the Company or make arrangements satisfactory to the
Committee for payment of any federal, state and local taxes required by law to
be withheld on account of such taxable event. Subject to approval by the
Committee, the Optionee may elect to have the minimum withholding obligation
satisfied, in whole or in part, by authorizing the Company to withhold from
shares of Common Stock to be issued or transferring to the Company, a number of
shares of Common Stock with an aggregate fair market value that would satisfy
the withholding amount due. The Optionee acknowledges and agrees that the
Company or any Subsidiary of the Company has the right to deduct from payments
of any kind otherwise due to the Optionee, or from the Option Shares to be
issued in respect of an exercise of this Stock Option, any federal, state or
local taxes of any kind required by law to be withheld with respect to the
issuance of Option Shares to the Optionee.

     10.  MISCELLANEOUS PROVISIONS.

          (a) EMPLOYMENT. This Option does not confer upon the Optionee any
rights with respect to employment or continuation of employment or the Service
Relationship with the Company, nor shall it interfere with any right of the
Company to terminate such employment or Service Relationship at anytime.

          (b) EQUITABLE RELIEF. The parties hereto agree and declare that legal
remedies may be inadequate to enforce the provisions of this Agreement and that
equitable relief, including specific performance and injunctive relief, may be
used to enforce the provisions of this Agreement.

          (c) CHANGE AND MODIFICATIONS. This Agreement may not be orally
changed, modified or terminated, nor shall any oral waiver of any of its terms
be effective. This Agreement may be changed, modified or terminated only by an
agreement in writing signed by the Company and the Optionee.

                                      -7-
<PAGE>   8

          (d) GOVERNING LAW. This Agreement shall be governed by and construed
in accordance with the laws of the State of Delaware (or the state of
incorporation of any successor corporation) without regard to conflict of law
principles.

          (e) HEADINGS. The headings are intended only for convenience in
finding the subject matter and do not constitute part of the text of this
Agreement and shall not be considered in the interpretation of this Agreement.

          (f) SAVING CLAUSE. If any provision(s) of this Agreement shall be
determined to be illegal or unenforceable, such determination shall in no manner
affect the legality or enforceability of any other provision hereof.

          (g) NOTICES. All notices, requests, consents and other communications
shall be in writing and be deemed given when delivered personally, by telex or
facsimile transmission or when received if mailed by first class registered or
certified mail, postage prepaid. Notices to the Company or the Optionee shall be
addressed as set forth underneath their signatures below, or to such other
address or addresses as may have been furnished by such party in writing to the
other.

          (h) BENEFIT AND BINDING EFFECT. This Agreement shall be binding upon
and shall inure to the benefit of the parties hereto, their respective
successors, permitted assigns, and legal representatives. The Company has the
right to assign this Agreement, and such assignee shall become entitled to all
the rights of the Company hereunder to the extent of such assignment.

          (i) COUNTERPARTS. For the convenience of the parties and to facilitate
execution, this Agreement may be executed in two or more counterparts, each of
which shall be deemed an original, but all of which shall constitute one and the
same document.

                            [Signature Page Follows]

                                      -8-
<PAGE>   9

     The foregoing Agreement is hereby accepted and the terms and conditions
thereof hereby agreed to by the undersigned as of the date first above written.

                                        MCK Communications, Inc.

                                        By: /s/ Paul K. Zurlo
                                            ------------------------------------
                                            Name: Paul K. Zurlo
                                            Title: Chief Financial Officer

                                        Address:

                                            117 Kendrick Street
                                            Needham, MA 02494

     The foregoing Agreement is hereby accepted and the terms and conditions
thereof hereby agreed to by the undersigned as of the date first above written.

                                        OPTIONEE:

                                        /s/ Glenda Davis
                                        ----------------------------------------
                                        Glenda Davis

                                        Optionee's Address:

                                        DESIGNATED BENEFICIARY:

                                        ----------------------------------------
                                        Name:

                                        Beneficiary's Address:

                                        ----------------------------------------

                                        ----------------------------------------

                                        ----------------------------------------

<PAGE>   10

                                   APPENDIX A

                          STOCK OPTION EXERCISE NOTICE

MCK Communications, Inc.
117 Kendrick Street
Needham, MA 02494

     Pursuant to the terms of my Non-Qualified Stock Option Agreement dated
March 13, 2001 (the "Agreement") I, ___________________________ [Insert name],
hereby [Circle One] partially/fully exercise such option by including herein
payment in the amount of $__________ representing the purchase price for
______________ [Fill in number of Option Shares] option shares. I have chosen
the following form(s) of payment:

          [ ] 1. Cash;
          [ ] 2. Certified or bank check payable to MCK Communications, Inc.; or
          [ ] 3. Other (as described in the Agreement (please describe))

                                        Sincerely yours,

                                        ----------------------------------------
                                        Glenda Davis

                                        Address:

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