The SO-24A allows supervisors to silently monitor employee phones without disrupting the activity at their workstation. The information gathered may be used for quality purposes, to train, motivate even assist customer service and telemarketing representatives. A supervisor may enter the conversation by dialing a ” .” A cassette recorder output permits automatic or manual recording of conversations. The SO-24A features improved audio and can now be easily expanded to 240 stations by installing additional 24 line units. The SO-24A can be programmed with a 2, 3 or 4 digit dial up code to match station extension numbers.