Plantronics S20 Telephone Headset System w/Amplifier & Over-the-Head or Ear Headset S20 Telephone Headset System • Connects to single- or multi-line phones All-in-one, under-the-telephone accessory deck includes premium amplifier (PLNA20) and DuoSet™ convertible headset (PLNH141) for over-the-head or over-the-ear use. Online indicator, headset stand and cord management system. Audible and visual cues simplify adjustment of tone control, mute and incoming/outgoing volume. Handy in-use indicator lets others know when you’re on the phone. Plug and play with seamless telephone integration sets up in minutes. Compatible with Handset Lifter (PLNHL10), sold separately.