Communication apparatus

摘要

An apparatus includes a direct-current direction detection unit configured to detect a change of direct-current direction on a telephone line through which the apparatus and an exchanger are coupled; a voltage change detection unit configured to detect a change of voltage on the line; a first control unit configured to transmit a reception completion signal to the exchanger when receiving telephone number; a first determination unit configured to determine whether polarity reversal of the line occurs in a period from reception of the telephone number to transmission of the reception completion signal; a second determination unit configured to determine whether the polarity reversal occurs in a period from transmission of the reception completion signal to reception of a calling signal; and a second control unit configured not to display the received telephone number on a display unit when the polarity reversal occurs in at least one of the periods.

主权项

1. A communication apparatus comprising:
a direct-current direction detection unit configured to detect a change of direction of a direct-current on a telephone line through which the communication apparatus and an exchanger are coupled to each other; a voltage change detection unit configured to detect a change of voltage on the telephone line; a display unit configured to display a telephone number of a caller apparatus that is coupled to the telephone line; a first control unit configured to perform control such that a reception completion signal is transmitted to the exchanger when the telephone number is received from the exchanger; a first determination unit configured to determine that a polarity reversal of the telephone line occurs in a first period when the change of direction of the direct-current on the telephone line is detected in the first period, the first period being a period from the time when the telephone number is received to the time when the reception completion signal is transmitted; a second determination unit configured to determine that a polarity reversal of the telephone line occurs in a second period when the change of voltage on the telephone line is detected in the second period, the second period being a period from the time when the reception completion signal is transmitted to the time when a calling signal for calling the communication apparatus is received; and a second control unit configured to perform control such that the received telephone number is not displayed on the display unit, when it is determined that the polarity reversal of the telephone line occurs in at least one of the first period and the second period.