Railways Act, 1989
59 Communication between passengers and railway servant in charge of train.
A railway administration shall provide and maintain in every train carrying passengers, such efficient means of communication between the passengers and the railway servant in charge of the train as may be approved by the Central Government :
Provided that where the railway administration is satisfied that the means of communication provided in a train are being misused, it may cause such means to be disconnected in that train for such period as it thinks, fit.
Provided further that the Central Government may specify the circumstances under which a railway administration may be exempted from providing such means of communication in any train.