Plantronics T20 2-line telephone with convertible headset T20 Two-Line Telephone with Convertible Headset Multi-featured with volume/tone control, ringer sound adjustment, flash and redial, and mute with indicator light. Noise canceling microphone. Convertible headset adjusts for over-the-head stability or over-the-ear convenience. On-line indicator and headset stand included. Cable connects to existing telephone jacks.