A communication apparatus comprising: communication means (101, 102, 103) for performing communication with a base station using one of a plurality of communication lines, read-out means for reading out identification information from each of a plurality of storage media (6, 7, 8) each storing identification information about a communication line, wherein said communication means is arranged to determine a plurality of communication lines corresponding to the plurality of storage media based on the identification information read out from the plurality of storage media by said read-out means, and perform communication with a base station using one of the plurality of determined communication lines; and characterized by comprising: control means for controlling said communication means to execute a search process of searching for a communicable base station at an interval determined for each of the plurality of determined communication lines, and set a standby state for an incoming call based on a result of the search process, wherein said control means is arranged to control the interval of the search process to be executed by said communication means for a communication line that is not set in the standby state among the plurality of determined communication lines in accordance with a number of communication lines in the standby state among the plurality of determined communication lines. communication means (101, 102, 103) for performing communication with a base station using one of a plurality of communication lines, read-out means for reading out identification information from each of a plurality of storage media (6, 7, 8) each storing identification information about a communication line, wherein said communication means is arranged to determine a plurality of communication lines corresponding to the plurality of storage media based on the identification information read out from the plurality of storage media by said read-out means, and perform communication with a base station using one of the plurality of determined communication lines; and characterized by comprising: control means for controlling said communication means to execute a search process of searching for a communicable base station at an interval determined for each of the plurality of determined communication lines, and set a standby state for an incoming call based on a result of the search process, wherein said control means is arranged to control the interval of the search process to be executed by said communication means for a communication line that is not set in the standby state among the plurality of determined communication lines in accordance with a number of communication lines in the standby state among the plurality of determined communication lines. control means for controlling said communication means to execute a search process of searching for a communicable base station at an interval determined for each of the plurality of determined communication lines, and set a standby state for an incoming call based on a result of the search process, wherein said control means is arranged to control the interval of the search process to be executed by said communication means for a communication line that is not set in the standby state among the plurality of determined communication lines in accordance with a number of communication lines in the standby state among the plurality of determined communication lines.