The Engage 55 is designed for use with computer (MAC or Windows) ONLY (NOT a mobile and NOT most deskphones). If you have a phone with a USB headset port you can use it with that instead. Designed with hot-deskers and hybrid workers in mind, it's very transportable between desks or home and office. Perfect for users who need the security, quality or range of DECT wireless (rather than Bluetooth). All are compatible with all major softphone applications.