Jabra/GN Cisco EHs Adapter enables remote Headset Hookswitch Control (EHS) with Jabra Jabra 6470, Jabra 9470, and the latest generation of Cisco Unified IP phones. This means that users can answer and end calls up to 300 ft. away from their desks. The seamless integration of handset and headset allows users to benefit from enhanced mobility and the ability to multitask while on a call. The wireless freedom improves work efficiency and ergonomics througout the day. Jabra EHS Adapter is a plug-and-play solution that converts from the HHC standard used in Cisco phones to the DHSG standard used in Jabra headsets – and vice versa. Handset-Headset compatibility

GN/Jabra EHs Adapter is compatible with these Cisco IP Phones: 7942G, 7945G, 7962G, 7965G and 7975G. Cisco Unified IP Phone release 8.3(3) will enable the HHC functionality.   Do not order this adapter if your phone is not listed or if you don't have the Jabra 6400 or 9400 series wireless headsets

For more information.  See Jabra EHS information  and Jabra EHS Link 22 datasheet