Here is a list of all the Sennheiser Electronic Hookswitch cords that we have, or at least know of. Feel free to poke around and see if you find the right one for you!

Sennheiser Electronic Hookswitch for Aastra Phones (DISCONTINUED)
Catalog # 2173
SEN/EHS/AASTRA
Set up - TBD
Sennheiser Electronic Hookswitch for Alcatel Phones
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
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
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
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
SEN/EHS/CISCO 7900 SERIES
Set up - Sennheiser Cisco Hookswitch Setup
P/N 504103/CEHS-CI 01
Sennheiser Electronic Hookswitch for Cisco 8900 & 9900 Series Phones
SEN/EHS/CISCO 8900-9900 SERIES
Set up - Sennheiser Cisco Hookswitch Setup
P/N 504533/CEHS-CI 02
Sennheiser Electronic Hookswitch for Cisco 8941 & 8945 Series Phones
SEN/EHS/CISCO 8941-8945
Set up - Sennheiser Cisco Hookswitch Setup
P/N 507234
Sennheiser Electronic Hookswitch for Cisco SPA Series Phones
SEN/EHS/CISCO SPA SERIES
Set up - Sennheiser Cisco Hookswitch Setup
P/N 506038/CEHS-CI 03
Sennheiser Electronic Hookswitch for Mobile Phones (Compatible with lightning adapter.)
SEN/EHS/MOBILEPHONE
Set up - Sennheiser Mobile EHS Setup (Cat #2161)
P/N 506033/CEHS-MB 01
Sennheiser Electronic Hookswitch for Panasonic Phones
SEN/EHS/PANASONIC
Set up - Sennheiser Panasonic EHS Setup (Cat #2296)
P/N 506077
Sennheiser Electronic Hookswitch for Polycom Phones
SEN/EHS/POLYCOM
Set up - Sennheiser Polycom EHS Setup (Cat #1778)
P/N 504104/CEHS-PO 01
Sennheiser Electronic Hookswitch for ShoreTel Phones
ShoreTel phones are already capable of remote answering, adding EHS adds ring detection
SEN/EHS/SHORETEL
Set up - Sennheiser Shoretel EHS Setup (Cat #2142)
P/N 504590/CEHS-SH 01
Sennheiser Electronic Hookswitch for Siemens & Unify Phones
SEN/EHS/SIEMENS-UNIFY
Set up - Sennheiser Siemens, Unify, & Aastra EHS Setup (Cat #1786)
P/N 504105/CEHS-DHSG
Sennheiser Electronic Hookswitch for Snom Phones
SEN/EHS/SNOM
Set up - Sennheiser Snom EHS Setup (Cat #1787)
P/N 504101/CEHS-SN 01