The M12 Vista Universal Amplifier connects Plantronics H-Series headsets to almost any phone and offer ergonomically designed volume, headset/handset, and mute controls. The Plantroics M12 Amp can be used with any "H-series" headset from barebones voice tube models like the Plantronics H51 Supra Headset - New, to advanced noise canceling models like the Plantronics H361N SupraPlus Noise Canceling Headset - New. The amplifier plugs into the handset jack on your phone and works with most single or multi-line telephones.