A teleprinter is a machine which works on electromagnetic principles and used for transmitting message from one place to another if both the ends are connected are connected with teleprinter exchange (called telex). The teleprinter consists of two machines with a standard typewriter keyboard placed at the two ends of transmission and reception of message. Teleprinter is hired from the post and telegraph department. Each subscriber to telex service is allotted a code number and it is linked to the nearest telephone exchange. The telex machines are also used to receive and send telegrams. Telex service is available in four big cities of India like Bombay (Mumbai), Delhi, Calcutta and Madras (Chennai).