A butt-set is used to test the telephone line at selective points such as the telco NID box or where the line connects to the phone or payphone. The butt-set can also be used to monitor a phones activity on the line such as dial outpulsing.

• Integrated circuit design
• Tone (DTMF) or pulse (Rotary)
• Line powered for talk, monitor or dialing function
• Built-in ringer
• Built-in polarity guard
• Last number redial
• Mute button. This button operates only as long as user keeps it depressed
• Includes polarity test. LED lights up green when polarity is correct
• Talk/Mon (monitor) switch (MON position allows line monitoring without disruption)