EXHIBIT 10.27

SUMMARY OF DIRECTOR COMPENSATION PLAN

On May 31, 2005, the Board of Directors of Sonus Networks, Inc. (the “Company”)
approved a compensation program for non-employee directors. The cash
compensation for non-employee directors is set forth below:

·       $20,000 per year for serving as a board member with no committee
assignments;

·       $23,750 per year for serving as a board member, and on one committee
other than the audit committee;

·       $27,500 per year for serving as a board member, and on the audit
committee;

·       $27,500 per year for serving as a board member, and on two committees
other than the audit committee;

·       $31,250 per year for serving as a board member, and on the audit
committee and one other committee; or

·       $37,500 per year for serving as a board member, and as chairman of the
audit committee.

Directors also are eligible to be reimbursed for reasonable out-of pocket
expenses incurred in connection with attendance at board of director or
committee meetings. Non-employee directors receive equity compensation under the
Company’s Amended and Restated 1997 Stock Incentive Plan as set forth below:

·       50,000 shares upon commencement of board service; and

·       20,000 shares annually thereafter.

Each option grant vests over a four-year period with 25% of the number of
options vesting one year from the date of grant and monthly thereafter at the
rate of 2.0833% for each month of service completed by the director.

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