| 摘要 |
PROBLEM TO BE SOLVED: To save power in standby and incoming call arrival, and to prolong a standby time by the power saving by efficiently switching ON/OFF of the power supply of a plurality of radio communication devices mounted on voice speech devices. SOLUTION: A cellular phone mounted with PHS and WLAN performs a standby operation with the PHS as long as the cellular phone exists within a PHS zone, irrespective of whether or not the cellular phone exists within a WLAN zone. Only when an incoming call arrives when the cellular phone is in a standby state in PHS (only PHS is powered on), the WLAN is powered on, and if the cellular phone exists within the WLAN zone, the incoming call is temporarily disconnected and a return call is transmitted by VoIP with the WLAN (call back). In this case, the PHS is kept in an off state. In contrast, if the cellular phone is out of the WLAN zone when receiving the incoming call, the incoming call is disconnected in the same way, and then, the WLAN is turned off and a return call is made by VoIP with the PHS. Meanwhile if a call back destination cannot be identified, the incoming call is received by the PHS without any change. COPYRIGHT: (C)2006,JPO&NCIPI
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