v3.26.1
REVENUE RECOGNITION - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
REVENUE RECOGNITION    
Total revenue $ 162,606 $ 181,279
United States    
REVENUE RECOGNITION    
Total revenue 72,578 82,695
Europe, Middle East and Africa    
REVENUE RECOGNITION    
Total revenue 39,070 45,499
Asia Pacific    
REVENUE RECOGNITION    
Total revenue 40,927 43,179
Other    
REVENUE RECOGNITION    
Total revenue 10,031 9,906
Product revenue    
REVENUE RECOGNITION    
Total revenue 68,114 81,991
Product revenue | Cloud and Edge    
REVENUE RECOGNITION    
Total revenue 26,259 31,861
Product revenue | IP Optical Networks    
REVENUE RECOGNITION    
Total revenue 41,855 50,130
Product revenue | Sales to enterprise customers    
REVENUE RECOGNITION    
Total revenue 21,516 23,232
Product revenue | Sales to service provider customers    
REVENUE RECOGNITION    
Total revenue 46,598 58,759
Product revenue | Indirect sales through channel partner program    
REVENUE RECOGNITION    
Total revenue 19,329 22,735
Product revenue | Direct sales    
REVENUE RECOGNITION    
Total revenue 48,785 59,256
Product revenue | United States    
REVENUE RECOGNITION    
Total revenue 20,941 29,341
Product revenue | Europe, Middle East and Africa    
REVENUE RECOGNITION    
Total revenue 16,962 19,460
Product revenue | Asia Pacific    
REVENUE RECOGNITION    
Total revenue 27,934 31,039
Product revenue | Other    
REVENUE RECOGNITION    
Total revenue 2,277 2,151
Service    
REVENUE RECOGNITION    
Total revenue 94,492 99,288
Service revenue (maintenance)    
REVENUE RECOGNITION    
Total revenue 63,667 66,422
Service revenue (maintenance) | Cloud and Edge    
REVENUE RECOGNITION    
Total revenue 50,232 50,768
Service revenue (maintenance) | IP Optical Networks    
REVENUE RECOGNITION    
Total revenue 13,435 15,654
Service revenue (maintenance) | United States    
REVENUE RECOGNITION    
Total revenue 33,733 33,324
Service revenue (maintenance) | Europe, Middle East and Africa    
REVENUE RECOGNITION    
Total revenue 14,683 17,383
Service revenue (maintenance) | Asia Pacific    
REVENUE RECOGNITION    
Total revenue 9,230 9,400
Service revenue (maintenance) | Other    
REVENUE RECOGNITION    
Total revenue 6,021 6,315
Service revenue (professional services)    
REVENUE RECOGNITION    
Total revenue 30,825 32,866
Service revenue (professional services) | Cloud and Edge    
REVENUE RECOGNITION    
Total revenue 23,021 24,962
Service revenue (professional services) | IP Optical Networks    
REVENUE RECOGNITION    
Total revenue 7,804 7,904
Service revenue (professional services) | United States    
REVENUE RECOGNITION    
Total revenue 17,904 20,030
Service revenue (professional services) | Europe, Middle East and Africa    
REVENUE RECOGNITION    
Total revenue 7,425 8,656
Service revenue (professional services) | Asia Pacific    
REVENUE RECOGNITION    
Total revenue 3,763 2,740
Service revenue (professional services) | Other    
REVENUE RECOGNITION    
Total revenue $ 1,733 $ 1,440