**EXHIBIT31.2**

**CERTIFICATIONPURSUANT TOSECTION 302 OF THE SARBANES-OXLEY ACT OF 2002**

I,Ellen B. Richstone, Chief Financial Officer, of Sonus Networks, Inc.,certify that:

1.                 Ihave reviewed this Quarterly Report on Form 10-Q for the periodended March 31, 2006 (“Quarterly Report”) of Sonus Networks, Inc.(the “Registrant”);

2.                 Basedon my knowledge, this Quarterly Report does not contain any untrue statement ofa material fact or omit to state a material fact necessary to make thestatements made, in light of the circumstances under which such statements weremade, not misleading with respect to the period covered by this QuarterlyReport;

3.                 Basedon my knowledge, the financial statements, and other financial informationincluded in this Quarterly Report, fairly present in all material respects thefinancial condition, results of operations and cash flows of the Registrant asof, and for, the periods presented in this Quarterly Report;

4.                 TheRegistrant’s other certifying officer and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for theRegistrant and have:

(a)          Designedsuch disclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision, to ensure that materialinformation relating to the Registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period in which this Quarterly Report is being prepared;

(b)         Designedsuch internal control over financial reporting or caused such internal controlover financial reporting to be designed under our supervision, to providereasonable assurance regarding the reliability of financial reporting and thepreparation of financial statements for external purposes in accordance withgenerally accepted accounting principles;

(c)          Evaluatedthe effectiveness of the Registrant’s disclosure controls and procedures andpresented in this Quarterly Report our conclusions about the effectiveness ofthe disclosure controls and procedures, as of the end of the period covered bythis Quarterly Report based on such evaluation; and

(d)         Disclosedin this Quarterly Report any change in the Registrant’s internal control overfinancial reporting that occurred during the Registrant’s most recent fiscalquarter that has materially affected, or is reasonably likely to materiallyaffect, the Registrant’s internal control over financial reporting; and

5.                 TheRegistrant’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to theRegistrant’s auditors and the audit committee of the Registrant’s board ofdirectors:

(a)          Allsignificant deficiencies and material weaknesses in the design or operation ofinternal control over financial reporting which are reasonably likely toadversely affect the Registrant’s ability to record, process, summarize andreport financial information; and

(b)         Anyfraud, whether or not material, that involves management or other employees whohave a significant role in the Registrant’s internal control over financialreporting.
| Date: May 8, 2006 | /s/ ELLEN  B. RICHSTONE                                  |
|------------------------|----------------------------------------------------------|
|                   | Ellen B. Richstone                                       |
|                   | *Chief Financial Officer  (Principal Financial Officer)* |

 

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