The W6KM handset builds on the proven W6 by adding the TOUCHSWITCH volume control. Light pressure on the + end of the switch increases the listening volume; light pressure on the - end decreases the volume. An important feature of TOUCH-SWITCH is that the volume automatically resets to normal when the handset is hung up allowing the W6KM to meet ADA requirement; each user can set the volume according to individual need. The W6KM is compatible only with phone systems using carbon microphones.