Portable telephone and communication method therefor

A portable telephone includes a radio section, a main body storage section, an external storage section, and control sections. The radio section conforms to a plurality of communication systems. The main body storage section stores data representing a plurality of operators corresponding to mobile telephone systems and frequencies allocated to the plurality of operators. The external storage section stores a plurality of operators who provide communication services. The control sections control communication by different mobile telephone systems, acquire predetermined specification data associated with communication, perform communication at first on the basis of the specification data and at least one of the data stored in the main body storage section and the data stored in the external storage section, and then determine a cell search range for communication by another control section, thereby performing a cell search upon limiting the cell search range to a frequency band limited relative to a cell search range set without any specification data. A communication method for a portable telephone is also disclosed.