DEBT	12 Months Ended
Dec. 31, 2018
Debt Disclosure [Abstract]
DEBT	DEBT Proposed Offering of Convertible Senior Note On November 13, 2018, the Company announced that it intended to offer, subject to market conditions and other factors, $150.0 million aggregate principal amount of convertible senior notes due 2023 in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended. The Company expected to grant the initial purchasers a 30-day option to purchase up to an additional $25.0 million aggregate principal amount of such notes, solely to cover over-allotments, if any. On that same day, the Company decided not to proceed with its previously-announced offering and consequently did not sell any securities as part of such offering. The Company believed that then-current market conditions were not conducive for an offering on terms that would be in the best interests of the Company's stockholders. In connection with this offering, the Company incurred $1.0 million of expense, primarily for professional fees, which is included as a component of General and administrative expense in the Company's consolidated statement of operations for the year ended December 31, 2018. Assumed Senior Secured Credit Agreement On the Merger Date and in connection with the Merger, the Company assumed GENBAND's Senior Secured Credit Agreement (the "Prior Credit Agreement" with Silicon Valley Bank ("SVB"), which had outstanding borrowings and letters of credit totaling $17.9 million and $2.9 million, respectively, and an average interest rate of 4.67%. GENBAND had entered into the Prior Credit Agreement with SVB effective July 1, 2016, with two of its operating subsidiaries as borrowers and GENBAND as the guarantor. The Prior Credit Agreement had a maturity date of July 1, 2019 and provided for revolving loans, including letters of credit and swingline loans, not to exceed $50 million in total, with potential further increases of $75 million available for a total revolving line of credit of up to $125 million. The Prior Credit Agreement was superseded by a Senior Secured Credit Facilities Credit Agreement, as amended, which was entered into on December 21, 2017 and is discussed below. Senior Secured Credit Facility On December 21, 2017, the Company entered into a Senior Secured Credit Facilities Credit Agreement (as amended, the “Credit Facility”) by and among the Company, as a guarantor, Sonus Networks, Inc., as the borrower (“Borrower”), SVB, as administrative agent (in such capacity, the “Administrative Agent”), issuing lender, swingline lender and lead arranger and the lenders party thereto (each referred to individually as a “Lender”, and collectively, the “Lenders”), which refinanced the Prior Credit Agreement. The Credit Facility includes $100 million of commitments, the full amount of which is available for revolving loans, a $15 million sublimit that is available for letters of credit and a $15 million sublimit that is available for swingline loans. The Credit Facility is scheduled to mature in December 2021, subject to a springing maturity if, on or before July 14, 2020, the existing promissory note issued to certain shareholders is not converted or extended to March 2022 or later. The Credit Facility contains procedures for additional financial institutions to become lenders or for any existing lender to increase its commitment under the facility, subject to an available increase of $50 million for all incremental commitments under the Credit Facility. On June 24, 2018, the Company amended the Credit Facility to, among other things, permit the Edgewater Acquisition and related transactions. The indebtedness and other obligations under the Credit Facility are unconditionally guaranteed on a senior secured basis by the Company and each other material U.S. domestic subsidiary of the Company (collectively, the "Guarantors"). The Credit Facility is secured by first-priority liens on substantially all of the assets of the Borrower and the Guarantors, including the Company. The Credit Facility requires periodic interest payments on outstanding borrowings until maturity. The Borrower may prepay all revolving loans under the Credit Facility at any time without premium or penalty (other than customary LIBOR breakage costs), subject to certain notice requirements. Revolving loans under the Credit Facility bear interest at the Borrower’s option at either the Eurodollar (LIBOR) rate plus a margin ranging from 2.50% to 3.00% per year or the base rate (the highest of the Federal Funds rate plus 0.50%, or the prime rate announced from time to time in The Wall Street Journal) plus a margin ranging from 1.50% to 2.00% per year (such margins being referred to as the “Applicable Margin”). The Applicable Margin varies depending on the Company’s consolidated leverage ratio (as defined in the Credit Facility). The base rate and the LIBOR rate are each subject to a zero percent floor. The Borrower is charged a commitment fee ranging from 0.25% to 0.40% per year on the daily amount of the unused portions of the commitments under the Credit Facility. Additionally, with respect to all letters of credit outstanding under the Credit Facility, the Borrower is charged a fronting fee of 0.125% per year and an outstanding letter of credit fee equal to the Applicable Margin for base rate loans ranging from 1.50% to 2.00% times the amount of the outstanding letters of credit. The Credit Facility requires compliance with certain financial covenants, including a minimum consolidated quick ratio, minimum consolidated interest coverage ratio and maximum consolidated leverage ratio, all of which are defined in the Credit Facility and tested on a quarterly basis. In addition, the Credit Facility contains various covenants that, among other restrictions, limit the Company’s and its subsidiaries’ ability to enter into certain types of transactions, including, but not limited to: incurring or assuming indebtedness, making acquisitions or engaging in mergers, making investments, repurchasing equity and paying dividends, selling or otherwise transferring assets, changing the nature of its business and amending or making prepayments on certain junior debt. The Company was in compliance with all covenants of the Credit Facility as of December 31, 2018 and 2017. The Credit Facility contains events of default that are customary for a secured credit facility. If an event of default relating to bankruptcy or other insolvency events with respect to a borrower occurs, all obligations under the Credit Facility will immediately become due and payable. If any other event of default exists under the Credit Facility, the lenders may accelerate the maturity of the obligations outstanding under the Credit Facility and exercise other rights and remedies, including charging a default rate of interest equal to 2.00% per year above the rate that would otherwise be applicable. In addition, if any event of default exists under the Credit Facility, the lenders may commence foreclosure or other actions against the collateral. If any default exists under the Credit Facility, or if the Borrower is unable to make any of the representations and warranties as stated in the Credit Facility at the applicable time, the Borrower will be unable to borrow funds or have letters of credit issued under the Credit Facility, which, depending on the circumstances prevailing at that time, could have a material adverse effect on the Borrower’s liquidity and working capital. At December 31, 2018, the Company had an outstanding debt balance of $55.0 million at a weighted average interest rate of 5.96% and $2.7 million of outstanding letters of credit at an interest rate of 1.75% under the Credit Facility. At December 31, 2017, the Company had an outstanding debt balance of $20 million at an interest rate of 4.51% and $2.9 million of outstanding letters of credit at an interest rate of 2.00% under the Credit Facility. Promissory Note In connection with the Merger, on October 27, 2017, the Company issued a promissory note for $22.5 million to certain of GENBAND's equity holders (the "Promissory Note"). The Promissory Note does not amortize and the principal thereon is payable in full on the third anniversary of its execution. Interest on the Promissory Note is payable quarterly in arrears and accrued at a rate of 7.5% per year for the first six months after issuance, and thereafter at a rate of 10% per year. The failure to make any payment under the Promissory Note when due and, with respect to payment of any interest, the continuation of such failure for a period of thirty days thereafter, constitutes an event of default under the Promissory Note. If an event of default occurs under the Promissory Note, the payees may declare the entire balance of the Promissory Note due and payable (including principal and accrued and unpaid interest) within five business days of the payees' notification to the Company of such acceleration. Interest that is not paid on the interest payment date will increase the principal amount of the Promissory Note. At December 31, 2018, the Promissory Note balance was $24.1 million, comprised of $22.5 million of principal, plus $1.6 million of interest converted to principal.

DEBT

Proposed Offering of Convertible Senior Note

On November 13, 2018, the Company announced that it intended to offer, subject to market conditions and other factors, $150.0 million aggregate principal amount of convertible senior notes due 2023 in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended. The Company expected to grant the initial purchasers a 30-day option to purchase up to an additional $25.0 million aggregate principal amount of such notes, solely to cover over-allotments, if any. On that same day, the Company decided not to proceed with its previously-announced offering and consequently did not sell any securities as part of such offering. The Company believed that then-current market conditions were not conducive for an offering on terms that would be in the best interests of the Company's stockholders. In connection with this offering, the Company incurred $1.0 million of expense, primarily for professional fees, which is included as a component of General and administrative expense in the Company's consolidated statement of operations for the year ended December 31, 2018.

Assumed Senior Secured Credit Agreement

On the Merger Date and in connection with the Merger, the Company assumed GENBAND's Senior Secured Credit Agreement (the "Prior Credit Agreement" with Silicon Valley Bank ("SVB"), which had outstanding borrowings and letters of credit totaling $17.9 million and $2.9 million, respectively, and an average interest rate of 4.67%. GENBAND had entered into the Prior Credit Agreement with SVB effective July 1, 2016, with two of its operating subsidiaries as borrowers and GENBAND as the guarantor. The Prior Credit Agreement had a maturity date of July 1, 2019 and provided for revolving loans, including letters of credit and swingline loans, not to exceed $50 million in total, with potential further increases of $75 million available for a total revolving line of credit of up to $125 million. The Prior Credit Agreement was superseded by a Senior Secured Credit Facilities Credit Agreement, as amended, which was entered into on December 21, 2017 and is discussed below.

Senior Secured Credit Facility

On December 21, 2017, the Company entered into a Senior Secured Credit Facilities Credit Agreement (as amended, the “Credit Facility”) by and among the Company, as a guarantor, Sonus Networks, Inc., as the borrower (“Borrower”), SVB, as administrative agent (in such capacity, the “Administrative Agent”), issuing lender, swingline lender and lead arranger and the lenders party thereto (each referred to individually as a “Lender”, and collectively, the “Lenders”), which refinanced the Prior Credit Agreement. The Credit Facility includes $100 million of commitments, the full amount of which is available for revolving loans, a $15 million sublimit that is available for letters of credit and a $15 million sublimit that is available for swingline loans. The Credit Facility is scheduled to mature in December 2021, subject to a springing maturity if, on or before July 14, 2020, the existing promissory note issued to certain shareholders is not converted or extended to March 2022 or later. The Credit Facility contains procedures for additional financial institutions to become lenders or for any existing lender to increase its commitment under the facility, subject to an available increase of $50 million for all incremental commitments under the Credit Facility. On June 24, 2018, the Company amended the Credit Facility to, among other things, permit the Edgewater Acquisition and related transactions.

The indebtedness and other obligations under the Credit Facility are unconditionally guaranteed on a senior secured basis by the Company and each other material U.S. domestic subsidiary of the Company (collectively, the "Guarantors"). The Credit Facility is secured by first-priority liens on substantially all of the assets of the Borrower and the Guarantors, including the Company.

The Credit Facility requires periodic interest payments on outstanding borrowings until maturity. The Borrower may prepay all revolving loans under the Credit Facility at any time without premium or penalty (other than customary LIBOR breakage costs), subject to certain notice requirements.

Revolving loans under the Credit Facility bear interest at the Borrower’s option at either the Eurodollar (LIBOR) rate plus a margin ranging from 2.50% to 3.00% per year or the base rate (the highest of the Federal Funds rate plus 0.50%, or the prime rate announced from time to time in The Wall Street Journal) plus a margin ranging from 1.50% to 2.00% per year (such margins being referred to as the “Applicable Margin”). The Applicable Margin varies depending on the Company’s consolidated leverage ratio (as defined in the Credit Facility). The base rate and the LIBOR rate are each subject to a zero percent floor.

The Borrower is charged a commitment fee ranging from 0.25% to 0.40% per year on the daily amount of the unused portions of the commitments under the Credit Facility. Additionally, with respect to all letters of credit outstanding under the Credit Facility, the Borrower is charged a fronting fee of 0.125% per year and an outstanding letter of credit fee equal to the Applicable Margin for base rate loans ranging from 1.50% to 2.00% times the amount of the outstanding letters of credit.

The Credit Facility requires compliance with certain financial covenants, including a minimum consolidated quick ratio, minimum consolidated interest coverage ratio and maximum consolidated leverage ratio, all of which are defined in the Credit Facility and tested on a quarterly basis. In addition, the Credit Facility contains various covenants that, among other restrictions, limit the Company’s and its subsidiaries’ ability to enter into certain types of transactions, including, but not limited to: incurring or assuming indebtedness, making acquisitions or engaging in mergers, making investments, repurchasing equity and paying dividends, selling or otherwise transferring assets, changing the nature of its business and amending or making prepayments on certain junior debt. The Company was in compliance with all covenants of the Credit Facility as of December 31, 2018 and 2017.

The Credit Facility contains events of default that are customary for a secured credit facility. If an event of default relating to bankruptcy or other insolvency events with respect to a borrower occurs, all obligations under the Credit Facility will immediately become due and payable. If any other event of default exists under the Credit Facility, the lenders may accelerate the maturity of the obligations outstanding under the Credit Facility and exercise other rights and remedies, including charging a default rate of interest equal to 2.00% per year above the rate that would otherwise be applicable. In addition, if any event of default exists under the Credit Facility, the lenders may commence foreclosure or other actions against the collateral.

If any default exists under the Credit Facility, or if the Borrower is unable to make any of the representations and warranties as stated in the Credit Facility at the applicable time, the Borrower will be unable to borrow funds or have letters of credit issued under the Credit Facility, which, depending on the circumstances prevailing at that time, could have a material adverse effect on the Borrower’s liquidity and working capital.

At December 31, 2018, the Company had an outstanding debt balance of $55.0 million at a weighted average interest rate of 5.96% and $2.7 million of outstanding letters of credit at an interest rate of 1.75% under the Credit Facility. At December 31, 2017, the Company had an outstanding debt balance of $20 million at an interest rate of 4.51% and $2.9 million of outstanding letters of credit at an interest rate of 2.00% under the Credit Facility.

Promissory Note

In connection with the Merger, on October 27, 2017, the Company issued a promissory note for $22.5 million to certain of GENBAND's equity holders (the "Promissory Note"). The Promissory Note does not amortize and the principal thereon is payable in full on the third anniversary of its execution. Interest on the Promissory Note is payable quarterly in arrears and accrued at a rate of 7.5% per year for the first six months after issuance, and thereafter at a rate of 10% per year. The failure to make any payment under the Promissory Note when due and, with respect to payment of any interest, the continuation of such failure for a period of thirty days thereafter, constitutes an event of default under the Promissory Note. If an event of default occurs under the Promissory Note, the payees may declare the entire balance of the Promissory Note due and payable (including principal and accrued and unpaid interest) within five business days of the payees' notification to the Company of such acceleration. Interest that is not paid on the interest payment date will increase the principal amount of the Promissory Note. At December 31, 2018, the Promissory Note balance was $24.1 million, comprised of $22.5 million of principal, plus $1.6 million of interest converted to principal.