MEANS OF COMMUNICATION AND ENGINE WHISTLE CODE GR 4.18
Means of communication
1. No passenger train or mixed train shall be dispatched from any station, unless every passenger carriage is provided with means by which communication can be made with the Guard or the LP.
2. The above rules shall not applya. Passenger or mixed train in case of complete or partial failure of vacuum. b. Such particular train as may be exempted under approved special instructions.
3. If the railway administration is satisfied that mischievous use of the means of communication referred to above is prevalent, it may, notwithstanding anything contained in the above rule, direct the disconnection, for the time being, of the means of communication provided in all or any of the passenger carriage in any such train.
