Complete Plantronix wireless headset telephone systems comes with everything you need including amplifier, headset, and telephone keypad to start using your wireless headset telephone as a stand alone telephone. The amplifier base unit plugs directly into the existing telephone jack.  Plug the headset into the wirless telephone keypad and you are ready to start talking!  Wireless telephone systems are not headsets and will not work with existing desktop telephones. These are replacements for single line telephones. Do not order these for your office PBX or digital phone system, it will NOT work.  For a totally wireless home headset solution, we recommend the new Plantronics CS55H.