RECEIVE-ONLY PORTABLE TERMINAL, SONAR SIGNAL TRANSMITTER AND COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a receive-only mobile terminal, a sonar signal transmitter and communication system where a user can early recognize the arrival of a phone call to portable telephone even when the power supply of the portable telephone is interrupted or the portable telephone is located at a remote place without the use of a communication system other than an exchange station of the portable telephone system and without the need for extension or revision of the communication system of the exchange system of the portable telephone. SOLUTION: The receive-only mobile terminal is in pair with a portable telephone terminal by which a caller and a called party make a wireless speech, has the same telephone number as that given to the telephone terminal, is provided with a reception detection section that receives and detects a wireless call signal including an ID signal (caller synchronizing signal identification information) sent from an exchange station or the like to call the telephone terminal, a notice means that informs a carrier about the detection of the call signal by means of vibration or pushing part of the body of the carrier other than sound when the reception detection section detects the call signal or the like and a display section that displays the information of the ID signal or the like in characters, and has a communication function of the reception function only with respect to the telephone station.