Patent ID: 7787603

Claim:
A telephone apparatus comprising: a first call signal detecting unit that detects a signal transmitted via a public telephone line as a first call signal if the signal has a predetermined frequency and continues for a predetermined time period; an identification information acquiring unit that executes an acquiring operation of acquiring source identification information for the signal transmitted via the public telephone line; a source identification information acquisition control unit that controls the acquiring operation of the identification information acquiring unit; and a determining unit that determines whether the identification information acquiring unit has acquired the source identification information, wherein when the first call signal detecting unit detects the first call signal, the source identification information acquisition control unit controls the identification information acquiring unit to execute the acquiring operation for the signal transmitted via the public telephone line after the first call signal if the determining unit determines that the identification information acquiring unit has not acquired the source identification information, and does not control the identification information acquiring unit to execute the acquiring operation for the signal transmitted via the public telephone line after the first call signal if the determining unit determines that the identification information acquiring unit has acquired the source identification information.