Tone-selective waystation dialing system interconnecting "message" and regular telephone line

Although railway dispatchers' telephone circuits should normally be entirely separate from other telephone facilities, there are times when interconnection is desirable. This paper describes dial equipment which would complete such connections without the aid of an operator, and without using the existing "Type 60" selectors. This system utilizes resonant-reed oscillators and relays in the voice spectrum. It requires little power (no standby power required at the way-station) and has low bridging losses. Tuned "guard" circuits preclude switching response to voice currents.