A portable telephone has an external earphone set electrically connected thereto by a jack plug and socket. The earphone set includes a microphone, at least one speaker, and a remote control unit having a display and a control switch. The portable telephone performs a calling operation depending on an...http://www.google.com/patents/US6459911?utm_source=gb-gplus-sharePatent US6459911 - Portable telephone equipment and control method therefor
