Sonus Networks

Prospectus Summary

YOU SHOULD READ THE FOLLOWING SUMMARY TOGETHER WITH THE MORE DETAILED INFORMATION REGARDING US, THE COMMON STOCK BEING SOLD IN THIS OFFERING AND OUR FINANCIAL STATEMENTS, INCLUDING THE NOTES TO THOSE STATEMENTS, APPEARING ELSEWHERE IN THIS PROSPECTUS. UNLESS OTHERWISE INDICATED, THIS PROSPECTUS ASSUMES:

- THE CONVERSION OF OUR OUTSTANDING SHARES OF REDEEMABLE CONVERTIBLE PREFERRED STOCK INTO AN AGGREGATE OF 32,319,074 SHARES OF COMMON STOCK UPON THE CLOSING OF THIS OFFERING; AND - THAT THE UNDERWRITERS DO NOT EXERCISE THEIR OPTION GRANTED BY US TO PURCHASE ADDITIONAL SHARES IN THIS OFFERING.