(networking, telecommunications) A type of transmission technology in which signaling is separate from the data being transmitted, using one or more channels for transmitting data or voice information and one out-of-band channel for performing signaling functions.

(Britain) A time signal transmitted on radio by the BBC every hour and consisting of five short beeps followed by a longer one, with the longer one coinciding with the start of the hour.

(telephony) An audible signal on a voice phone line that sounds more frequently than a standard busy signal, indicating that no transmission path to the called phone number is available.

(US, Australia) Any of the large metal boxes containing traffic signal controls, found at roadsides and intersections, and often made available by the local council for artistic work.

plural of Greenwich Time Signal

plural of traffic signal box