Abstract: A power supply control method in a portable communication device achieves reduced power consumption. A main CPU sends an operation check request to a sub CPU. When the sub CPU performs radio communication for location registration, the sub CPU sends an operation check response back to the main CPU. When the time required from transmission of the operation check request to reception of its response exceeds a predetermined time-out period or the response fails to be received within the predetermined time-outperiod, it is determined that no external communication is performed by the sub controller and therefore the sub controller is powered off.

Abstract: A mobile station and frequency band detection method in a mobile communication system in which a base station communicates with a mobile station in one of a plurality of set frequency bands. In this detection method, when a frequency band of a radio signal from a base station is to be detected, detection of a frequency band which was used in the past for actual communication with any of base stations or a predetermined frequency band is performed before detection of other frequency bands.

Abstract: A facsimile system has an operation controller for generating overhead information including a called party address, a demand for confirmation of recording, instructing for the transmission of a document. The document is scanned to produce binary picture data. A storage memory records the overhead information and encodes the picture data. The designated receiving party is called and the stored data is read out of the memory and transmitted, along with a demand for confirmation of the recording of the received information. As the transmitting side demands a recording confirmation response, it designates an address to which the response to the demand should be sent, which is done upon the completion of the recording of the picture signals. The facsimile machine at the initial transmitting party's station records in its recording means the contents of the response to the demand for confirmation of recording.