Sennheiser EHS Catalog # & Setup. Sennheiser Electronic Hookswitch for Aastra Phones (DISCONTINUED) Catalog # 2173 SEN/EHS/AASTRA Set up - TBD Sennheiser Electronic Hookswitch for Alcatel Phones Catalog # 1783 SEN/EHS/ALCATEL Set up - Sennheiser Alcatel EHS Set Up P/N 504102/CEHS-AL 01 Sennheiser Electronic Hookswitch for Avaya 1400, 1600, 2400 & 9000 Series Phones Catalog # 2083 SEN/EHS/AVAYA 1400-1600-2400-9000 SERIES Set up - Sennheiser Avaya 1400,1600, 2400, & 9000 series EHS Setup (Cat #2083) P/N 504536/CEHS-AV 03 Sennheiser Electronic Hookswitch for Avaya 1400 & 9000 Series Phones Catalog # 2164 SEN/EHS/AVAYA 1400-9000 SERIES Set up - Sennheiser Avaya 1400 & 9000 EHS Setup (Cat #2164) P/N 504589/CEHS-AV 04 Sennheiser Electronic Hookswitch for Avaya 2420, 4600 & 5000 Series Phones Catalog # 2162 SEN/EHS/AVAYA 2420-4600-5000 SERIES Set up - Sennheiser Avaya 2420, 4600, & 5000 EHS Setup (Cat #2162) P/N 506037/CEHS-AV 05 Sennheiser Electronic Hookswitch for Cisco 7900 Series Phones…