REVENUE AND MAJOR CUSTOMERS (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 26, 2020 USD ($) Customer	Sep. 28, 2019 USD ($) Customer	Sep. 26, 2020 USD ($) Customer	Sep. 28, 2019 USD ($)	Mar. 28, 2020 USD ($) Customer
Revenue from External Customer [Line Items]
Contract with Customer, Asset, before Allowance for Credit Loss, Current	$ 4,300,000		$ 4,300,000		$ 3,700,000
Revenue, Remaining Performance Obligation, Current	146,600		146,600
Net revenues	410,969,000	$ 461,709,000	$ 766,689,000	$ 909,476,000
Revenue From Contracts With Customers, Percentage Associated With Non-cancellable Maintenance And Support Contracts			90.00%
Contract with Customer, Liability	212,800,000		$ 212,800,000		$ 208,500,000
Capitalized Contract Cost, Gross	4,700,000		4,700,000
Revenue, Remaining Performance Obligation, Noncurrent	68,400		68,400
Revenue, Remaining Performance Obligation, Amount	215,000.0		215,000.0
Contract with Customer, Liability, Revenue Recognized	50,900,000
Headset [Member]
Revenue from External Customer [Line Items]
Net revenues	202,840,000	206,292,000	377,590,000	424,942,000
Product
Revenue from External Customer [Line Items]
Net revenues	347,677,000	395,137,000	639,135,000	777,882,000
Product | United States
Revenue from External Customer [Line Items]
Net revenues	159,532,000	187,935,000	303,821,000	386,716,000
Product | Europe and Africa
Revenue from External Customer [Line Items]
Net revenues	114,875,000	111,672,000	192,493,000	212,778,000
Product | Asia Pacific
Revenue from External Customer [Line Items]
Net revenues	52,548,000	68,821,000	97,979,000	126,073,000
Product | Americas, excluding U.S.
Revenue from External Customer [Line Items]
Net revenues	20,722,000	26,709,000	44,842,000	52,315,000
Product | Total international net revenues [Member]
Revenue from External Customer [Line Items]
Net revenues	188,145,000	207,202,000	335,314,000	391,166,000
Voice
Revenue from External Customer [Line Items]
Net revenues	49,069,000	98,453,000	99,750,000	202,300,000
Video
Revenue from External Customer [Line Items]
Net revenues	95,768,000	90,392,000	161,795,000	150,640,000
Service
Revenue from External Customer [Line Items]
Net revenues	63,292,000	66,572,000	127,554,000	131,594,000
Service | United States
Revenue from External Customer [Line Items]
Net revenues	24,245,000	25,192,000	48,237,000	51,238,000
Service | Europe and Africa
Revenue from External Customer [Line Items]
Net revenues	15,524,000	17,301,000	32,012,000	33,175,000
Service | Asia Pacific
Revenue from External Customer [Line Items]
Net revenues	19,021,000	18,632,000	37,854,000	36,228,000
Service | Americas, excluding U.S.
Revenue from External Customer [Line Items]
Net revenues	4,502,000	5,447,000	9,451,000	10,953,000
Service | Total international net revenues [Member]
Revenue from External Customer [Line Items]
Net revenues	$ 39,047,000	$ 41,380,000	$ 79,317,000	$ 80,356,000
Net Revenues [Member] | Customer Concentration Risk [Member]
Revenue from External Customer [Line Items]
Number of Major Customers, Ten Percent Or Greater, Net Revenues | Customer	2	2
Net Revenues [Member] | Customer Concentration Risk [Member] | ScanSource
Revenue from External Customer [Line Items]
Concentration risk percentage	25.00%	21.70%	18.30%	19.60%
Net Revenues [Member] | Customer Concentration Risk [Member] | Ingram Micro
Revenue from External Customer [Line Items]
Concentration risk percentage	18.30%	16.80%	19.70%	16.80%
Accounts Receivable [Member] | Customer Concentration Risk [Member]
Revenue from External Customer [Line Items]
Number of major customers, ten percent or greater, net accounts receivable | Customer	2		2		3
Accounts Receivable [Member] | Customer Concentration Risk [Member] | ScanSource
Revenue from External Customer [Line Items]
Concentration risk percentage			24.90%		17.30%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Ingram Micro
Revenue from External Customer [Line Items]
Concentration risk percentage			23.30%		22.20%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Synnex Corp.
Revenue from External Customer [Line Items]
Concentration risk percentage					15.60%
Minimum [Member]
Revenue from External Customer [Line Items]
Revenue From Contracts With Customers, Credit Term			30 days
Maximum [Member]
Revenue from External Customer [Line Items]
Revenue From Contracts With Customers, Credit Term			90 days