Sound Power Telephone System is communication system for communicating between areas or rooms like the wheel house, the engine room and steering room when necessary. Specially this system allows for emergency communication without the requirement for any external power supply. For the conversation the speech energy received from the transmitter microphone is converted into the electrical energy and there converted again into the speech signal after reaching the handset of the mate telephone set through the on-board wiring. It was tested the IEC60945 standard and approved CE by DNV class. It obtained the type approval from DNV class.