Radio Circuit 2 : Two-way radio equipment, one of the several acceptable types of alarm circuits, used for communications between the fire alarm dispatcher and various fire stations
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}