The JPL EHS-3 DS-DHSG Siemens/Unify-Aastra/Mitel Adapter Cord electronically connects your DECT headset base to your telephone. It enables remote operation, answer/end calls, eliminating the need for a mechanical handset lifter. Suitable for wireless headset use with various phones. Compatible with Siemens/Unify OpenStage 30, 40, 60, 80, OptiPoint Basic, Std, Adv, Eco 410, 420, 500, 600 phone models and Aastra /Mitel 5370, 5370ip, 5380, 5380ip, 6739i, 6771, 6773, 6773ip, 6775, 6775ip, 7434ip, 7444ip, 6735i, 6737i, 6753i, 6755i and 6757i phone models.