Exhibit 10.18

SONUS NETWORKS, INC.

AMENDED AND RESTATED

2000 EMPLOYEE STOCK PURCHASE PLAN

EFFECTIVE AS OF MARCH 1, 2008

---





|1.  |  | Purpose                                                            |  | 1
|--- |  | ------------------------------------------------------------------ |  | -
|2.  |  | Definitions                                                        |  | 1
|3.  |  | Eligibility                                                        |  | 2
|4.  |  | Offering Periods                                                   |  | 2
|5.  |  | Participation                                                      |  | 2
|6.  |  | Method of Payment of Contributions                                 |  | 3
|7.  |  | Grant of Option                                                    |  | 3
|8.  |  | Exercise of Option                                                 |  | 4
|9.  |  | Delivery                                                           |  | 4
|10. |  | Voluntary Withdrawal; Termination of Employment                    |  | 4
|11. |  | Interest                                                           |  | 5
|12. |  | Stock                                                              |  | 5
|13. |  | Administration                                                     |  | 5
|14. |  | Designation of Beneficiary                                         |  | 5
|15. |  | Transferability                                                    |  | 6
|16. |  | Use of Funds                                                       |  | 6
|17. |  | Reports                                                            |  | 6
|18. |  | Adjustments Upon Changes in Capitalization; Corporate Transactions |  | 6
|19. |  | Amendment or Termination                                           |  | 7
|20. |  | Notices                                                            |  | 7
|21. |  | Conditions Upon Issuance of Shares                                 |  | 8
|22. |  | Term of Plan; Effective Date                                       |  | 8

---





SONUS NETWORKS, INC.

AMENDED AND RESTATED  2000 EMPLOYEE STOCK PURCHASE PLAN  EFFECTIVE AS OF MARCH 1, 2008

The following constitute the provisions of the Amended and Restated 2000 Employee Stock Purchase Plan of Sonus Networks, Inc., effective as of
March 1, 2008.

1.     Purpose

The purpose of the Plan is to provide employees of the Company and its Designated Subsidiaries with an opportunity to purchase Common Stock of the Company. It is
the intention of the Company to have the Plan qualify as an "Employee Stock Purchase Plan" under Section 423 of the Code. The provisions of the Plan shall, accordingly, be construed so as to
extend and limit participation in a manner consistent with the requirements of that section of the Code.

2.     Definitions

2.1Boardmeans the Board of Directors of the Company.

2.2Codemeans the Internal Revenue Code of 1986, as amended.

2.3Common Stockmeans the Common Stock, par value $0.001 per share, of the Company.

2.4Companymeans Sonus Networks, Inc., a Delaware corporation.

2.5Compensationmeans all regular straight time compensation including commissions but shall not include
payments for overtime, shift premium, incentive compensation, incentive payments, bonuses and other irregular or infrequent compensation or benefits.

2.6Continuous Status as an Employeemeans the absence of any interruption or termination of service as an
Employee. Continuous Status as an Employee shall not be considered interrupted in the case of (i) sick leave; (ii) military leave; (iii) any other leave of absence approved by the
Administrator, provided that such leave is for a period of not more than 90 days, unless reemployment upon the expiration of such leave is guaranteed by contract or statute, or unless provided
otherwise pursuant to Company policy adopted from time to time; or (iv) transfers between locations of the Company or between the Company and its Designated Subsidiaries.

2.7Contributionsmeans all amounts credited to the account of a participant pursuant to the Plan.

2.8Corporate Transactionmeans a merger or consolidation of the Company with and into another person or the
sale, transfer, or other disposition of all or substantially all of the Company's assets to one or more persons (other than any wholly-owned subsidiary of the Company) in a single transaction or
series of related transactions, unless securities possessing more than 50% of the total combined voting power of the survivor's or acquiror's outstanding securities, or the securities of any parent
thereof, are held by a person or persons who held the voting securities of the Company immediately prior to such transaction.

2.9Designated Subsidiariesmeans the Subsidiaries which have been designated by the Board from time to time in
its sole discretion as eligible to participate in the Plan.

2.10Employeemeans any person, including an Officer, who is customarily employed for at least twenty
(20) hours per week and more than five (5) months in a calendar year by the Companyorone of its Designated Subsidiaries.

---



2.11Exchange Actmeans the Securities Exchange Act of 1934, as amended.

2.12Offering Datemeans the first business day of each Offering Period of the Plan.

2.13Offering Periodmeans a period of six (6) months commencing on March 1 and September 1
of each year.

2.14Officermeans a person who is an officer of the Company within the meaning of Section 16 of the
Exchange Act and the rules and regulations promulgated thereunder.

2.15Planmeans this Employee Stock Purchase Plan.

2.16Purchase Datemeans the last day of each Offering Period of the Plan.

2.17Purchase Pricemeans with respect to an Offering Period an amount equal to 85% of the Fair Market Value (as
defined in Section 7.2 below) of a Share of Common Stock on the Purchase Date.

2.18Sharemeans a share of Common Stock, as adjusted in accordance with Section 19 of the Plan.

2.19Subsidiarymeans a corporation, domestic or foreign, of which not less than 50% of the voting shares are
held by the Company or a Subsidiary, whether or not such corporation now exists or is hereafter organized or acquired by the Company or a Subsidiary.

3.     Eligibility

3.1    Any person who is an Employee as of the Offering Date of a given Offering Period shall be eligible to participate in such Offering Period under
the Plan, subject to the requirements of Section 5.1 and the limitations imposed by Section 423(b) of the Code.

3.2    Any
provisions of the Plan to the contrary notwithstanding, no Employee shall be granted an option under the Plan (i) if, immediately after the grant, such
Employee (or any other person whose stock would be attributed to such Employee pursuant to Section 424(d) of the Code) would own capital stock of the Company and/or hold outstanding options to
purchase stock possessing five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or of any subsidiary of the Company, or (ii) if such
option would permit his or her rights to purchase stock under all employee stock purchase plans (described in Section 423 of the Code) of the Company and its Subsidiaries to accrue at a rate
which exceeds Twenty-Five Thousand Dollars ($25,000) of the Fair Market Value (as defined in Section 7.2 below) of such stock (determined at the time such option is granted) for
each calendar year in which such option is outstanding at any time.

4.     Offering Periods

The Plan shall be generally implemented by a series of Offering Periods of six (6) months' duration, with new Offering Periods commencing on or about
March 1 and September 1 of each year (or at such other time or times as may be determined by the Board of Directors). The Plan shall continue until terminated in accordance with
Section 19 hereof. The Board of Directors of the Company shall have the power to change the duration and/or the frequency of Offering Periods with respect to future offerings without
stockholder approval if such change is announced to Employees at least five (5) days prior to the scheduled beginning of the first Offering Period to be affected.

5.     Participation

5.1    An eligible Employee may become a participant in the Plan by completing a subscription agreement on the form provided by the Company and filing
it with the Company's stock admin department prior to the applicable Offering Date, unless a later time for filing the subscription

2

---



agreement
is set by the Board for all eligible Employees with respect to a given Offering Period. The subscription agreement shall set forth the percentage of the participant's Compensation (subject
to Section 6.1 below) to be paid as Contributions pursuant to the Plan.

5.2    Payroll
deductions shall commence on the first payroll following the Offering Date and shall end on the last payroll paid on or prior to the Purchase Date for such
Offering Period to which the
subscription agreement is applicable, unless sooner terminated by the participant as provided in Section 10.

6.     Method of Payment of Contributions

6.1    A participant shall elect to have payroll deductions made on each payday during the Offering Period in an amount not less than one percent (1%)
and not more than twenty percent (20%) (or such other percentage as the Board may establish from time to time before an Offering Date) of such participant's Compensation on each payday during the
Offering Period. All payroll deductions made by a participant shall be credited to his or her account under the Plan. A participant may not make any additional payments into such account.

6.2    A
participant may discontinue his or her participation in the Plan as provided in Section 10. In addition, if Board of Directors of the Company has so announced
to Employees at least five (5) days prior to the scheduled beginning of the next Offering Period to be affected, a participant may, on one occasion only during each Offering Period, change the
rate of his or her Contributions with respect to the Offering Period by completing and filing with the Company a % change form authorizing a change in the payroll deduction rate. Any such change in
rate shall be effective as of the beginning of the next Offering Period following the date of filing of the % change form.

6.3    Notwithstanding
the foregoing, to the extent necessary to comply with Section 423(b)(8) of the Code and Section 3.2 herein, a participant's payroll
deductions may be decreased during any Offering Period scheduled to end during the current calendar year to 0%. Payroll deductions shall re-commence automatically at the rate provided in
such participant's subscription agreement at the beginning of the next Offering Period which is scheduled to end in the following calendar year, unless terminated by the participant as provided in
Section 10.

7.     Grant of Option

7.1    On the Offering Date of each Offering Period, each eligible Employee participating in such Offering Period shall be granted an option to purchase
on each Purchase Date a number of Shares of the Company's Common Stock determined by dividing such Employee's Contributions accumulated prior to such Purchase Date and retained in the participant's
account as of the Purchase Date by the applicable Purchase Price; provided however that the maximum number of Shares an Employee may purchase during each Offering Period shall be 2,500 Shares (subject
to any adjustment pursuant to Section 18 below), and provided further that such purchase shall be subject to the limitations set forth in Sections 3.2 and 12.

7.2    The
fair market value of the Company's Common Stock on a given date (the "Fair Market Value") shall be determined by the Board in its discretion based on the closing
sales price of the Common Stock for such date (or, in the event that the Common Stock is not traded on such date, on the immediately preceding trading date), as reported by the National Association of
Securities Dealers Automated Quotation ("Nasdaq") Global Select Market or, if such price is not reported, the mean of the bid and asked prices per share of the Common Stock as reported by Nasdaq or,
in the event the Common Stock is listed on a stock exchange, the Fair Market value per share shall be the closing sales price on such exchange on such date (or, in the event that the Common Stock is
not traded on such date, on the immediately preceding trading date), as reported in The Wall Street Journal.

3

---



8.     Exercise of Option

Unless a participant withdraws from the Plan as provided in Section 10, his or her option for the purchase of Shares will be exercised automatically on the
Purchase Date for each Offering Period, and the maximum number of full Shares subject to the option will be purchased at the applicable Purchase Price with the accumulated Contributions in his or her
account. No fractional Shares shall be issued. The Shares purchased upon exercise of an option hereunder shall be deemed to be transferred to the participant on the Purchase Date. During his or her
lifetime, a participant's option to purchase Shares hereunder is exercisable only by him or her.

9.     Delivery

As promptly as practicable after each Purchase Date of each Offering Period, the Company shall arrange the delivery to each participant. These shares will be
deposited into the participant's stock plan account. Any payroll contributions accumulated in a participant's account after a Purchase Date shall be returned to the participant.

10.   Voluntary Withdrawal; Termination of Employment

10.1    A participant may withdraw all but not less than all of the Contributions credited to his or her account under the Plan at any time prior to
each Purchase Date by giving written notice to the Company. All of the participant's Contributions credited to his or her account will be paid to him or her promptly after receipt of his or her notice
of withdrawal and his or her option for the current
period will be automatically terminated, and no further Contributions for the purchase of Shares will be made during the Offering Period.

10.2    Upon
termination of the participant's Continuous Status as an Employee prior to the Purchase Date of an Offering Period for any reason, including retirement or death,
the Contributions credited to his or her account will be returned to him or her or, in the case of his or her death, to the person or persons entitled thereto under Section 14, and his or her
option will be automatically terminated.

10.3    In
the event an Employee fails to remain in Continuous Status as an Employee of the Company for at least twenty (20) hours per week during the Offering Period in
which the employee is a participant, he or she will be deemed to have elected to withdraw from the Plan and the Contributions credited to his or her account will be returned to him or her and his or
her option terminated.

4

---



10.4    A participant's withdrawal from an offering will not have any effect upon his or her eligibility to participate in a succeeding offering or in any similar plan which
may hereafter be adopted by the Company.

11.   Interest

No interest shall accrue on the Contributions of a participant in the Plan.

12.   Stock

12.1    Subject to adjustment as provided in Section 18, the maximum number of Shares which shall be made available for sale under the Plan shall
be 1,200,000 Shares plus an automatic annual increase on January 1, 2001 and each January 1 thereafter equal to the lesser of (i) two percent (2%) of the Shares outstanding on the
last day of the immediately preceding fiscal year, and (ii) such number as the Board may determine. Notwithstanding the foregoing, and subject to adjustment in accordance with Section 18
no more than an aggregate of 25,000,000 Shares may be issued pursuant to this Plan. If the Board determines that, on a given Purchase Date, the number of shares with respect to which options are to be
exercised may exceed (i) the number of shares of Common Stock that were available for sale under the Plan on the Offering Date of the applicable Offering Period, or (ii) the number of
shares available for sale under the Plan on such Purchase Date, the Board may in its sole discretion provide that the Company shall make a pro rata allocation of the Shares of Common Stock available
for purchase on such Offering Date or Purchase Date, as applicable, in as uniform a manner as shall be practicable and as it shall determine in its sole discretion to be equitable among all
participants exercising options to purchase Common Stock on such Purchase Date. The Company may make pro rata allocation of the Shares available on the Offering Date of any applicable Offering Period
pursuant to the preceding sentence, notwithstanding any authorization of additional Shares for issuance under the Plan by the Company's stockholders subsequent to such Offering Date.

12.2    The
participant shall have no interest or voting right in Shares covered by his or her option until such option has been exercised.

12.3    Shares
to be delivered to a participant under the Plan will be registered in the name of the participant or pursuant to Section 14 below.

13.   Administration

The Board, or a committee named by the Board, shall supervise and administer the Plan and shall have full power to adopt, amend and rescind any rules deemed
desirable and appropriate for the administration of the Plan and not inconsistent with the Plan, to construe and interpret the Plan, and to make all other determinations necessary or advisable for the
administration of the Plan. The Board's determinations made in good faith on matters referred to in this Plan shall be final, binding and conclusive on all persons having or claiming any interest
under this Plan or an Award made pursuant hereto.

14.   Designation of Beneficiary

14.1    A participant may file a written designation of a beneficiary who is to receive any Shares and cash, if any, from the participant's
account under the Plan in the event of such participant's death subsequent to the end of an Offering Period but prior to delivery to him or her of such Shares and cash. In addition, a participant may
file a written designation of a beneficiary who is to receive any cash from the participant's account under the Plan in the event of such participant's death prior to the Purchase Date of an
Offering Period.

5

---



14.2    Such
designation of beneficiary may be changed by the participant at any time by written notice. In the event of the death of a participant and in the absence of a
beneficiary validly designated under the Plan who is living at the time of such participant's death, the Company shall deliver such Shares and/or cash to the executor or administrator of the estate of
the participant, or if no such executor or administrator has been appointed (to the knowledge of the Company), the Company, in its discretion, may deliver such Shares and/or cash to the spouse or to
any one or more dependents or relatives of the participant, or if no spouse, dependent or relative is known to the Company, then to such other person as the Company may designate.

15.   Transferability

Neither Contributions credited to a participant's account nor any rights with regard to the exercise of an option or to receive Shares under the Plan may be
assigned, transferred, pledged or otherwise disposed of in any way (other than by will, the laws of descent and distribution, or as provided in Section 14) by the participant. Any such attempt
at assignment, transfer, pledge or other disposition shall be without effect, except that the Company may treat such act as an election to withdraw funds in accordance with Section 10.

16.   Use of Funds

All Contributions received or held by the Company under the Plan may be used by the Company for any corporate purpose, and the Company shall not be obligated to
segregate such Contributions.

17.   Reports

Individual accounts will be maintained for each participant in the Plan.

18.   Adjustments Upon Changes in Capitalization; Corporate Transactions

18.1Adjustment.Subject to any required action by the stockholders of the Company, the number of shares covered
by each option under the Plan which has not yet been exercised and the number of Shares which have been authorized for issuance under the Plan but have not yet been placed under option (collectively,
the "Reserves"), as well as the maximum number of shares of Common Stock which may be purchased by a participant in an Offering Period, the number of shares of Common Stock set forth in
Section 12.1 above, and the price per Share of Common Stock covered by each option under the Plan which has not yet been exercised, shall be proportionately adjusted for any increase or
decrease in the number of issued Shares resulting from a stock split, reverse stock split, stock dividend, combination or reclassification of the Common Stock (including any such change in the number
of Shares of Common Stock effected in connection with a change in domicile of the Company), or any other increase or decrease in the number of Shares effected without receipt of consideration by the
Company; provided however that conversion of any convertible securities of the Company shall not be
deemed to have been "effected without receipt of consideration." Such adjustment shall be made by the Board, whose determination in that respect shall be final, binding and conclusive.

18.2Corporate Transactions.In the event of a dissolution or liquidation of the Company, any Offering Period
then in progress will terminate immediately prior to the consummation of such action, unless otherwise provided by the Board. In the event of a Corporate Transaction, each option outstanding under the
Plan shall be assumed or an equivalent option shall be substituted by the successor corporation or a parent or Subsidiary of such successor corporation. In the event that the successor corporation
refuses to assume or substitute for outstanding options, each Offering Period then in progress shall be shortened and a new Purchase Date shall be set (the "New Purchase Date"), as of which date any
Offering Period then in progress will terminate. The New Purchase Date shall be

6

---



on
or before the date of consummation of the transaction and the Board shall notify each participant in writing, at least ten (10) days prior to the New Purchase Date, that the Purchase Date
for his or her option has been changed to the New Purchase Date and that his or her option will be exercised automatically on the New Purchase Date, unless prior to such date he or she has withdrawn
from the Offering Period as provided in Section 10. For purposes of this Section 18, an option granted under the Plan shall be deemed to be assumed, without limitation, if, at the time
of issuance of the stock or other consideration upon a Corporate Transaction, each holder of an option under the Plan would be entitled to receive upon exercise of the option the same number and kind
of shares of stock or the same amount of property, cash or securities as such holder would have been entitled to receive upon the occurrence of the transaction if the holder had been, immediately
prior to the transaction, the holder of the number of Shares of Common Stock covered by the option at such time (after giving effect to any adjustments in the number of Shares covered by the option as
provided for in this Section 18); provided however that if the consideration received in the transaction is not solely common stock of the successor corporation or its parent (as defined in
Section 424(e) of the Code), the Board may, with the consent of the successor corporation, provide for the consideration to be received upon exercise of the option to be solely common stock of
the successor corporation or its parent equal in Fair Market Value to the per Share consideration received by holders of Common Stock in the transaction.

The
Board may, if it so determines in the exercise of its sole discretion, also make provision for adjusting the Reserves, as well as the price per Share of Common Stock covered by each
outstanding option, in the event that the Company effects one or more reorganizations, recapitalizations, rights offerings or other increases or reductions of Shares of its outstanding Common Stock,
and in the event of the Company's being consolidated with or merged into any other corporation.

19.   Amendment or Termination

19.1    The Board may at any time and for any reason terminate or amend the Plan. Except as provided in Section 18, no such termination of the
Plan may affect options previously granted, provided that the Plan or an Offering Period may be terminated by the Board on a Purchase Date or by the Board's setting a new Purchase Date with respect to
an Offering Period then in progress if the Board
determines that termination of the Plan and/or the Offering Period is in the best interests of the Company and the stockholders or if continuation of the Plan and/or the Offering Period would cause
the Company to incur adverse accounting charges as a result of the Plan. Except as provided in Section 18 and in this Section 19, no amendment to the Plan shall make any change in any
option previously granted which adversely affects the rights of any participant.

19.2    Without
stockholder consent and without regard to whether any participant rights may be considered to have been adversely affected, the Board (or its committee) shall
be entitled to change the Offering Periods, limit the frequency and/or number of changes in the amount withheld during an Offering Period, establish the exchange ratio applicable to amounts withheld
in a currency other than U.S. dollars, permit payroll withholding in excess of the amount designated by a participant in order to adjust for delays or mistakes in the Company's processing of properly
completed withholding elections, establish reasonable waiting and adjustment periods and/or accounting and crediting procedures to ensure that amounts applied toward the purchase of Common Stock for
each participant properly correspond with amounts withheld from the participant's Compensation, and establish such other limitations or procedures as the Board (or its committee) determines in its
sole discretion advisable which are consistent with the Plan.

20.   Notices

All notices or other communications by a participant to the Company under or in connection with the Plan shall be deemed to have been duly given when received in
the form specified by the Company at the location, or by the person, designated by the Company for the receipt thereof.

7

---



21.   Conditions Upon Issuance of Shares

Shares shall not be issued with respect to an option unless the exercise of such option and the issuance and delivery of such Shares pursuant thereto shall comply
with all applicable provisions of law, domestic or foreign, including, without limitation, the Securities Act of 1933, as amended, the Exchange Act, the rules and regulations promulgated thereunder,
applicable state securities laws and the requirements of any stock exchange upon which the Shares may then be listed, and shall be further subject to the approval of counsel for the Company with
respect to such compliance.

As
a condition to the exercise of an option, the Company may require the person exercising such option to represent and warrant at the time of any such exercise that the Shares are being
purchased only for investment and without any present intention to sell or distribute such Shares if, in the opinion of counsel for the Company, such a representation is required by any of the
aforementioned applicable provisions of law.

22.   Term of Plan; Effective Date

The Plan shall become effective upon the effective date of the Registration Statement on Form S-1 for the initial public offering of the
Company's Common Stock. It shall continue in effect for a term of twenty (20) years unless sooner terminated under Section 19.

8

---



QuickLinks