A red light on the phone's base indicates whether an incoming call should be answered on line one or line two. If you want to place a caller on hold, press the hold button; the light flashes until you press the hold button or the appropriate line button again. By placing one caller on hold, then dialing a second party and connecting the two lines with the conference button, you can have a three-way conference call.

The Plantronics T20 comes with a convertible headset that is light and comfortable to wear for long periods of time. The headset features a sturdy headband, padded flexible earpiece and headpiece, and a fully adjustable microphone. The microphone can be worn with the headband or with ear hanging hooks on either ear. The sound quality of the earpiece and microphone is very clear. A tone control lets you adjust the tonal quality of your incoming calls.

A noise-canceling microphone eliminates background noise, and makes your voice easily understandable to callers. You can adjust the volume level of the earpiece with a wheel on the side of the phone's base. The headset has a 4-foot cord with an adjustable clothing clip, providing you with freedom of movement. A convenient headset stand attaches to the base and keeps the headset within easy reach.