A specialized test set carried by telephone technicians to tap into copper phone lines. It features heavy-duty alligator clips or bed-of-nails connectors to bridge onto a twisted pair. Technicians use it to check for dial tone, monitor line noise, or dial out directly from a distribution frame or terminal block.
Grab your buttinsky and clip onto pair 42 at the demarc to see if we have dial tone.
The name comes from the ability to literally butt into an active phone conversation when clipping across a live pair.
Also heard as
- butt set
- butt-in set
- test set
Related terms
Demarc extension
The physical cabling that connects a service provider's termination point to the customer's networking equipment.
Local loop
The physical wiring connecting a customer premises to the nearest telephone exchange.
Punchdown
A mechanical connection method where solid copper wire is forced into a slotted metal clip.