Exhibit 10.3  Sonus
Networks, Inc.  7 Technology Park Drive, Westford, MA 01886  July 7,
2009  Mr. Kumar
K. Vishwanathan  Dear
Kumar:  I
am pleased to provide you in this letter (the Agreement) with the terms and
conditions of our offer of employment to you by Sonus Networks, Inc. (the Company).  1.             Position.  The Company agrees to employ you as Vice
President and Chief Architect, reporting to Guru Pai.  As the Companys organization evolves, in
addition to performing duties and responsibilities associated with the position
of Vice President and Chief Architect you may be assigned other management
duties and responsibilities as the Company may determine.  As
a full-time employee of the Company, you will be expected to devote your full
business time and energies to the business and affairs of the Company.  2.             Commencement Date/Nature of
Relationship.  Your employment shall
commence no later than August 3, 2009 (the Commencement Date).  No provision of this letter shall be
construed to create an express or implied employment contract for a specific
period of time.  Employment at Sonus
Networks, Inc. is considered at will and either you or the Company may
terminate the employment relationship at any time and for any reason or no
reason.  3.             Base Compensation.  Your initial base salary (Base Salary) will
be at the annualized rate of $195,000.00, less applicable state and federal
withholdings, paid twice monthly in accordance with the Companys normal
payroll practices.  4.             Target Bonus.  You will be eligible to participate in the
Sonus MBO Bonus Program during each year you are employed by the Company with a
target bonus of 50% of your then-current annual base salary (Target Bonus).  For 2009, your Target Bonus will be
pro-rated.  Specific objectives for your
Target Bonus for 2009 will be agreed upon with Guru Pai within the first sixty
(60) days of your employment for 2009. Your annual target bonus shall be paid
as soon as practicable following the Companys public disclosure of its
financial results for the applicable bonus year.  5.             Stock Option Grants.  You will be granted non-qualified options to
purchase 150,000 shares of common stock under the Companys 2007 Stock Plan,
subject to the terms of the Plan and the terms of the Companys stock option
agreement which shall reflect the terms of this Agreement.  The grant date will be on the earliest 15th
day of a month that next follows your Commencement Date or the first business
day thereafter if that day is not a business day.  The per share exercise price will be the per
share closing price of the Companys common stock on the grant date (2009
Option Exercise Price).  Subject to the
provisions of this Agreement, the options shall vest and become exercisable as
follows: (A) 25% of the shares (37,500 shares) shall vest on the first
anniversary of the Commencement Date and, (B) the remaining 75% of the
shares (112,500 shares) shall vest in equal monthly increments thereafter
through the fourth anniversary of the Commencement Date.  1


6.             Restricted Stock Grant.  You will be granted Restricted Shares of the
Companys common stock, $0.001 par value per share (Restricted Shares) as
follows:  (a)You will be
granted 75,000 shares of the Companys common stock under the Companys 2007
Stock Plan, subject to the terms of the Plan and the Companys restricted stock
agreement, which shall reflect the terms of this Agreement.  The grant date will be on the earliest 15th
day of a month that next follows your Commencement Date or the first business
day thereafter if that day is not a business day.  The Restricted Shares shall vest as follows: (A) 25%
of the Restricted Shares (18,750 Restricted Shares) shall vest on the first
anniversary of the Commencement Date and, (B) 75% of the Restricted Shares
(56,250 Restricted Shares) shall vest in six equal increments semi-annually
thereafter through the fourth anniversary of the Commencement Date;  (b)You may elect
under Section 83(b) of the Internal Revenue Code of 1986, as amended,
to be taxed at the time the Restricted Shares are acquired on the Grant Date (Section 83(b) Election).  A Section 83(b) Election, if made,
must be filed with the Internal Revenue Service within thirty (30) days of the
Grant Date.  You are obligated to pay to
the Company the amount of any federal, state, local or other taxes of any kind
required by law to be withheld with respect to the granting (if a Section 83(b) Election
is made) or vesting (if a Section 83(b) Election is not made) of the
shares.  If you do not make a Section 83(b) Election,
you shall satisfy such tax withholding obligations by delivery to the Company,
on each date on which shares vest, such number of shares that vest on such date
as have a fair market value (calculated using the last reported sale price of
the common stock of the Company on the NASDAQ Global Select Market on the
trading date immediately prior to such vesting date) equal to the amount of the
Companys withholding obligation; provided, however, that the total tax withholding
cannot exceed the Companys minimum statutory withholding obligations (based on
minimum statutory withholding rates for federal and state tax purposes,
including payroll taxes, that are applicable to such supplemental taxable
income).  Such delivery of shares to the
Company shall be deemed to happen automatically, without any action required on
your part, and the Company is hereby authorized to take such actions as are
necessary to effect such delivery of shares to the Company.  7.             Performance Stock Grant. Performance
Stock Grant. In addition to the grant of Restricted Shares described in
paragraph 6 above, you will be eligible to receive 75,000 shares of the Companys
common stock (also in the form of Restricted Shares) under the Companys 2007
Stock Plan, subject to the terms of the Plan and the Companys restricted stock
agreement, which shall reflect the terms of this Agreement.  Your grant of additional Restricted Shares
under this paragraph shall be conditioned upon your achieving and/or the Company
achieving (as determined by the CEO and Senior Vice President &
General Manager) during your employment certain performance metrics for each of
the three fiscal years ended December 31, 2009, 2010 and 2011.  You shall be eligible to be granted 1/3 of
such performance-based Restricted Shares after the conclusion of each such
fiscal year (that is, up to 25,000 per year). 
Any such additional grants will be made on the 15thday of the month after the month during which
the Company publicly reports its financial results for such year.  8.             Employment Eligibility.  In compliance with the Immigration Reform and
Control Act of 1986, you are required to establish your identity and employment
eligibility.  Therefore, on your first
day of employment you will be required to fill out an Employment Verification Form and
present documents in accordance with this form.  2


9.Benefits.  You will be entitled as an employee of the
Company to receive such benefits as are generally provided its employees in
accordance with Company policy as in effect from time to time.  Company benefits include group health, life
and dental insurance, and liberal holidays, vacation and 401K programs.  All employees begin accruing three (3) weeks
of vacation upon date of hire in accordance with Company policy.  The Company is committed to providing a
healthy work environment for every employee. 
Therefore, we provide a smoke free environment and require all employees
to comply.  The Company retains the right
to change, add or cease any particular benefit.  10.Confidentiality.  The Company considers the protection of its
confidential information, proprietary materials and goodwill to be very
important.  Therefore, as a condition of
your employment and the stock option and restricted stock grants described
above, you and the Company will become parties to a Noncompetition and
Confidentiality Agreement.  Two copies of
this agreement are sent with this offer letter. 
Both copies must be signed and returned to the Company prior to the
Commencement Date.  11.Termination and
Eligibility for Severance.  If
your employment with the Company is terminated by the Company without Cause (as
defined below) or you terminate your employment with the Company for Good
Reason (as defined below), the Company will provide you the following severance
and related post-termination benefits:  (a)a lump sum
payment equal to the sum of six-months of your then annual base salary and 50%
of your then target annual bonus, less applicable state and federal
withholdings;  (b)continuation of
payment of the Companys share of medical, dental and vision insurance premiums
for you and your dependents for the six (6) month period following the
termination of your employment; provided, that if immediately prior to the
termination of your employment you were required to contribute towards the cost
of such premiums as a condition of receiving such insurance, you may be
required to continue contributing towards the cost of such premiums under the
same terms and conditions as applied to you and your dependents immediately
prior to the termination of your employment in order to receive such continued
insurance coverage;  (c)any allowable
unreimbursed expenses and any accrued but unused vacation pay owing to you at
the time of termination;  (d)any stock
options granted to you by the Company to purchase the Companys common stock
that are unvested as of the termination date and would vest during the six (6) months
following your termination will accelerate and immediately vest and become
exercisable upon termination, and your stock options that are or become vested
will remain outstanding and exercisable for the shorter of three (3) years
following your termination date or the original remaining life of the options;
and  (e)any Restricted
Shares granted to you by the Company that are unvested as of the termination
date will accelerate and immediately vest upon termination, and any and all
restrictions on such Restricted Shares shall be terminated and any and all
legends shall be removed so that the shares be and are freely marketable.  The
Companys provision of the benefits described in Section 11(a), (b), (d) and
(e) above shall be contingent upon your execution of a release of all
claims of any kind or nature in favor of the Company in a form to be provided
by the Company (the Release Agreement), which Release Agreement must be
delivered to the Company within fifty-two (52) days following the termination
of your employment.  The  3


lump
sum payment described in Section 11(a) above shall be made on the
sixtieth (60) day following the termination of your employment, after the
Companys receipt of the executed Release Agreement and the expiration of any
revocation period described in the Release Agreement.  The Company shall have no further obligation
to you in the event your employment with the Company terminates at any time,
other than those obligations specifically set forth in this Section 11.  The
Company may terminate your employment at any time with or without Cause by
written notice to you specifying the date of termination.  You may terminate your employment with or
without Good Reason by providing written notice to the Company at least thirty
(30) days prior to the date of termination. 
If you seek to terminate your employment for Good Reason, the Company
shall have ten (10) business days following its receipt of written notice
of termination to cure the circumstance giving rise to Good Reason.  Upon a termination for Cause by the Company
or upon a termination without Good Reason, you will be entitled to accrued but
unpaid Base Salary and benefits through the date of termination only.  12.Definitions.  As used in this Agreement, the following
terms shall have the following meanings:  (a)Change in Control as used in this Agreement shall have the
meaning set forth on Annex A attached hereto.  (b)Good Reason as used in this Agreement means the occurrence
of any of the following without your consent: (A) a reduction in your
annual Base Salary set forth above; (B) the assignment to you of a lower
position in the organization in terms of your title, responsibility, authority
or status unless agreed to in writing by you, or (C) the relocation of the
Company to a location that is more than fifty (50) miles from the Companys current
headquarters location in Westford, MA.  (c)Cause as used in this Agreement means the occurrence of any
of the following: (i) your indictment for, formal admission to (including
a plea of guilty or nolo contendere
to), or conviction of a felony, a crime of moral turpitude, dishonesty, breach
of trust or unethical business conduct, or any crime involving the Company, (ii) gross
negligence or willful misconduct by you in the performance of your duties that
is likely to have an adverse affect on the Company or its reputation; (iii) your
commission of an act of fraud or dishonesty in the performance of your duties; (iv) repeated
failure by you to perform your duties which are reasonably and in good faith
requested in writing by the Chief Executive Officer of the Company or the Board
of Directors of the Company; (v) material breach of this Agreement by you,
which you do not cure within ten (10) days following receipt by you of
such written notice notifying you of such breach, or material breach by you of
any confidentiality agreement with the Company.  13.           Tax Implications of Termination
Payments.  Subject to this Section 13,
any payments or benefits required to be provided under Section 11 shall be
provided only after the date of your separation from service with the Company
as defined under Section 409A of the U.S. Internal Revenue Code of 1986,
as amended, and the guidance issued thereunder (Section 409A). The following
rules shall apply with respect to distribution of the payments and
benefits, if any, to be provided to you under Section 11:  (a)It is intended
that each installment of the payments and benefits provided under Section 11
shall be treated as a separate payment for purposes of Section 409A.  Neither the Company nor you shall have the
right to accelerate or defer the delivery of any such payments or benefits
except to the extent specifically permitted or required by Section 409A.  4


(b)If, as of the
date of your separation from service with the Company, you are not a specified
employee (each within the meaning of Section 409A), then each installment
of the payments and benefits shall be made on the dates and terms set forth in Section 11;
and  (c)If, as of the
date of your separation from service with the Company, you are a specified
employee (each, for purposes of this Agreement, within the meaning of Section 409A),
then:  (i)Each
installment of the payments and benefits due under Section 11 that, in
accordance with the dates and terms set forth herein, will in all
circumstances, regardless of when the separation from service occurs, be paid
within the short-term deferral period (as defined for the purposes of Section 409A)
shall be treated as a short-term deferral within the meaning of Treasury
Regulation Section 1.409A-1(b)(4) to the maximum extent permissible
under Section 409A; and  (ii)Each
installment of the payments and benefits due under Section 11 that is not
paid within the short-term deferral period or otherwise cannot be treated as a
short-term deferral within the meaning of Treasury Regulation Section 1.409A-1(b)(4) and
that would, absent this subsection, be paid within the six-month period
following your separation from service with the Company shall not be paid
until the date that is six months and one day after such separation from
service (or, if earlier, upon your death), with any such installments that are
required to be delayed being accumulated during the six-month period and paid
in a lump sum on the date that is six months and one day following your
separation from service and any subsequent installments, if any, being paid in
accordance with the dates and terms set forth herein; provided, however, that
the preceding provisions of this sentence shall not apply to any installment of
payments if and to the maximum extent that that such installment is deemed to
be paid under a separation pay plan that does not provide for a deferral of
compensation by reason of the application of Treasury Regulation 1.409A-1(b)(9)(iii) (relating
to separation pay upon an involuntary separation from service).  Any installments that qualify for the
exception under Treasury Regulation Section 1.409A-1(b)(9)(iii) must
be paid no later than the last day of the second taxable year following the
taxable year in which your separation from service occurs.  14.Section 409A
of the Code.  This
Agreement is intended to comply with the provisions of Section 409A and
this Agreement shall, to the extent practicable, be construed in accordance
therewith.  Terms used in this Agreement
shall have the meanings given such terms under Section 409A if and to the
extent required in order to comply with Section 409A.  Notwithstanding the foregoing, to the extent
that this Agreement or any payment or benefit hereunder shall be deemed not to
comply with Section 409A, then neither the Company, the Board of Directors
nor its or their designees or agents shall be liable to you or any other person
for any actions, decisions or determinations made in good faith.  15.Other
Agreements.  You
represent and warrant to the Company that you are not bound by any agreement
with a previous employer or other party which you would in any way violate by
accepting employment with the Company or performing your duties as an employee
of the Company.  You further represent
and warrant that, in the performance of your duties with the Company, you will
not utilize or  5


disclose
any confidential information in breach of an agreement with a previous employer
or any other party.  16.           Assignment.  This Agreement is personal in nature and
neither of the parties hereto shall, without the written consent of the other,
assign or otherwise transfer this Agreement or its obligations, duties and
rights under this Agreement; provided, however, that in the event of the
merger, consolidation, transfer or sale of all or substantially all of the
assets of the Company, this Agreement shall, subject to the provisions hereof,
be binding upon and inure to the benefit of such successor and such successor
shall discharge and perform all of the promises, covenants, duties and
obligations of the Company hereunder.  17.           General.  (a)Entire
Agreement; Modification.  This
Agreement along with the other agreements and Plans referenced herein contain
the entire agreement of the parties relating to the subject matter hereof, and
the parties hereto have made no agreements, representations or warranties
relating to the subject matter of this Agreement that are not set forth
otherwise herein (or in the other documents referenced herein).  This Agreement, along with the other
agreements and Plans referenced herein, supersede any and all prior agreements,
written or oral, between you and the Company. 
No modification of this Agreement shall be valid unless made in writing
and signed by the parties hereto.  (b)Severable
Provisions.  The
provisions of this Agreement are severable and if any one or more provisions
may be determined to be illegal or otherwise unenforceable, in whole or in
part, the remaining provisions of this Agreement shall nevertheless be binding
and enforceable.  Notwithstanding the
foregoing, if there are any conflicts between the terms of this Agreement and
the terms of any Plan document referred to in this Agreement, then the terms of
this Agreement shall govern and control. 
Except as modified hereby, this Agreement shall remain unmodified and in
full force and effect.  (c)Governing
Law.  This Agreement shall be
governed by and interpreted in accordance with the laws of the Commonwealth of
Massachusetts, without regard to the conflict of laws provisions hereof.  (d)Arbitration.  (i)Any
controversy, dispute or claim arising out of or relating to this Agreement or the
breach hereof which cannot be settled by mutual agreement will be finally settled
by binding arbitration in the commonwealth of Massachusetts, under the jurisdiction
of the American Arbitration Association or other mutually agreeable alternative
arbitration dispute resolution service, before a single arbitrator appointed in
accordance with the arbitration rules of the American Arbitration Association
or other selected service, modified only as herein expressly provided.  The arbitrator may enter a default decision
against any party who fails to participate in the arbitration proceedings.  (ii)The decision of
the arbitrator on the points in dispute will be final, non-  appealable and binding, and judgment on the
award may be entered in any court having jurisdiction thereof.  (iii)The fees and
expenses of the arbitrator will be shared equally by the parties, and each
party will bear the fees and expenses of its own attorney.  6


(iv)The parties
agree that this Section 13(d) has been included to resolve any disputes
between them with respect to this Agreement, and that this Section 13(d)    will be grounds for dismissal of any court
action commenced by either party with respect to this Agreement, other than
post-arbitration actions seeking to enforce an arbitration award or actions
seeking an injunction or temporary restraining order.  In the event that any court determines that
this arbitration procedure is not binding, or otherwise allows any litigation
regarding a dispute, claim, or controversy covered by this Agreement to
proceed, the parties hereto hereby waive, to the maximum extent allowed by law,
any and all right to a trial by jury in or with respect to such litigation.  (v)The parties
will keep confidential, and will not disclose to any person, except as may be
required by law or the rules and regulations of the Securities and Exchange
Commission or other government agencies, the existence of any controversy
hereunder, the referral of any such controversy to arbitration or the status or
resolution thereof.  (e)Notices.  All notices shall be in writing and shall be
delivered personally (including by courier), sent by facsimile transmission
(with appropriate documented receipt thereof), by overnight receipted courier
service (such as UPS or FedEx) or sent by certified, registered or express
mail, postage prepaid, to the Company at the following address:  General Counsel, Sonus Networks, Inc., 7
Technology Park Drive, Westford, MA 01886, and to you at the following address:                             .  Any such notice shall be deemed given when so
delivered personally, or if sent by facsimile transmission, when transmitted,
or, if by certified, registered or express mail, postage prepaid mailed,
forty-eight (48) hours after the date of deposit in the mail.  Any party may, by notice given in accordance
with this paragraph to the other party, designate another address or person for
receipt of notices hereunder.  (f)Counterparts.  This Agreement may be executed in more than
one counterpart, each of which shall be deemed to be an original, and all such
counterparts together shall constitute one and the same instrument.  You
may accept this offer of employment and the terms and conditions thereof by
confirming your acceptance in writing by July 10, 2009.  Please send your signed letter to the
company, or via e-mail to kharris@sonusnet.com which execution will evidence
your agreement with the terms and conditions set forth herein and therein.  We are enthusiastic about your joining us,
and believe that our technical and business goals will provide every
opportunity for you to achieve your personal and professional objectives.  ****  I
am looking forward to your joining the team to help us take Sonus to the next
level.   Very truly yours,/s/ Kathleen HarrisKathleen
  HarrisVice
  President of Human Resources  7


Accepted
by:   /s/ Kumar Vishwanathan
  
  7/6/09Kumar
  Vishwanathan
  
  Date  8


Annex A  A
Change in Control as used in this Agreement of which this Annex is a part
shall mean the first to occur of any of the following:  (a)           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 or its Affiliates), is or
becomes the beneficial owner (as defined in Rule 1 3d-3 under the
Exchange Act), directly or indirectly, of securities of the Company (not
including in the securities beneficially owned by such person any securities
acquired directly from the Company or you) representing fifty percent (50%) or
more of the combined voting power of the Companys then outstanding securities;
or  (b)           in the event that the individuals who
as of the date hereof constitute the Board of Directors, and any new director
whose election by the Board or nomination for election by the Companys
stockholders was approved by a vote of at least a majority of the Board then
still in office who either were members of the Board as of the date hereof or
whose election or nomination for election was previously so approved, cease for
any reason to constitute at least a majority thereof; or  (c)           the consummation of a merger or
consolidation of the Company with or the sale of the Company to any other
entity and, in connection with such merger, consolidation or sale; individuals
who constitute the Board immediately prior to the time any agreement to effect
such merger or consolidation is entered into fail for any reason to constitute
at least a majority of the board of directors of the surviving or acquiring
corporation following the consummation of such merger, consolidation or sale;  (d)           the stockholders of the Company
approve a plan of complete liquidation of the Company; or  (e)           the consummation of the sale or
disposition by the Company of all or substantially all of the Companys assets
to an entity not controlled by the Company.  9