Sennheiser UI770 Universal Interface Amplifier with Headset/Handset Switch
The UI770 is the ideal universal wideband Interface box that lets you switch directly between handset and headset, and between phone and PC. Connect a PC, standard phone, handset, a headset of the Sennheiser contact center or office series and even a dictaphone for voice recording.
The UI770 supports the possibility of limiting the speaker volume by simply setting a switch. This secures compliance with the Noise of work Directive from EU (EU Directive 2003/10/EC) and will result in a reduced maximum output level for the user.
More information: https://www.harriscomm.com/sennheiser-ui770-universal-interface-amplifier.html