A wireless telephone has a function of monitor-outputting an operation sound as an operation key is pressed. The wireless telephone can be operated in one of three modes, namely, none push-tone output mode, normal push-tone output mode and prolonged push-tone output mode. The operation sound is generated...http://www.google.fr/patents/US5343510?utm_source=gb-gplus-shareBrevet US5343510 - Wireless telephone
