Vibrating reed selective signaling system
Harold M. Pruden, Daniel F. Hoth · Electrical Engineering · 1949
IN MANY mobile radio systems now in service, the car is provided with a loud-speaker which is in operation at all times, the desired car being called by voice. Such an arrangement has the disadvantage that the occupants of all the telephone-equipped cars hear all conversations on their channel. However, all Bell System common carrier mobile telephone systems use selective signaling arrangements which enable the mobile service operator to ring a bell in the desired car by dialing the car's telephone number.