These "hot line" phones are designed to automatically dial a pre-programmed number as soon as the handset is lifted. They are commonly used for emergency help, customer service kiosks, or security desks.

: The hot wire is typically the smooth wire (black), while the neutral wire has ridges or grooves.

: Often used in Koontech VoIP phones to achieve instant "point-to-point" communication between two specific handsets. 3. Electrical Context: "Two Hot Lines"