A facsimile apparatus includes a storage unit, a first detection unit, and a second detection unit. The storage unit stores a parameter based on a connection standard of a telephone-line connected to the facsimile apparatus, and an apparatus direct-current resistance of the facsimile apparatus. The first detection unit detects a first voltage that is a voltage at a line-open time of a telephone line connected to the facsimile apparatus. The second detection unit detects a second voltage that is a voltage at a line-capture time of the telephone line. By using the first voltage, the second voltage, the parameter, and the apparatus direct-current resistance, a voltage to be a threshold for determination of line capture is determined. By using a voltage detected from the telephone line and the voltage to be the threshold determined by the first determination unit, whether the telephone line is captured is determined.

An information processing apparatus capable of preventing a user from unnecessarily taking a wasteful action. Whether a communication line is connected to the information processing apparatus and an off-hook state in the information processing apparatus are detected. Whether to turn on a display unit is controlled. When connection of the communication line to the information processing apparatus and the off-hook state are detected the display unit is controlled to turn on. When non-connection of the communication line to the information processing apparatus and the off-hook state are detected, the display unit is controlled not to turn on.

A communication control device for controlling communication performed over a communication line includes a voltage-value acquirer for acquiring a value of a line-to-line voltage of the communication line in an on-hook state, a first determiner for determining whether the voltage value is continuously equal to or lower than a threshold voltage for a first predetermined duration, a current-value acquirer for acquiring a value of a current flowing through the communication line in an off-hook state when the voltage value is continuously equal to or lower than the threshold voltage for the first predetermined duration, a second determiner for determining whether the current value is continuously equal to or smaller than a threshold current for a second predetermined duration, and a disconnection determiner for determining that the communication line is disconnected when the current value is continuously equal to or smaller than the threshold current for the second predetermined duration.

The present invention provides a technique that enables an image communication apparatus capable of performing voice communication and T.30 in-band FAX communication over the IP network to positively detect a CNG signal and achieve switching to FAX reception in the answerphone connection mode and the FAX/TEL-switching mode. The communication apparatus includes a MODEM that controls facsimile communication and a SLIC that controls a telephone. A selector includes switches for connecting the IP network and the MODEM, and switches for connecting the IP network and the SLIC. A CPU controls the switches of the selector such that signals from the IP network are supplied to both of the MODEM and the SLIC.

An image forming apparatus includes a first connection portion, a second connection portion, a communication processing portion, a switch processing portion, and a connection determination processing portion. To the switch processing portion, the first connection portion and the second connection portion are connected in parallel. The switch processing portion breaks a communication path between the second connection portion and the switch processing portion when the facsimile communication process is executed by the communication processing portion. The connection determination processing portion, when a predetermined determination start condition is satisfied, causes the switch processing portion to break the communication path, and then when a predetermined line voltage is applied to the switch processing portion, determines that a connection between the first connection portion and the public switched telephone network is normal.

The present invention is intended to inhibit off-hook using a hook key in an operation unit to make a caller ID function stably usable in an image communication apparatus connectable to a telephone line and having a caller ID display function. According to one embodiment, the image communication apparatus includes an off-hook unit configured to perform the off-hook using the hook key in the operation unit, a detection unit configured to detect polarity reversal of a telephone line, a receiving unit configured to receive an information service signal, which arrives via the telephone line, after the detection unit has detected the polarity reversal, and a control unit configured to perform control to inhibit the off-hook by the off-hook unit based on the detection of the polarity reversal by the detection unit.

The present invention provides a technique that enables an image communication apparatus capable of performing voice communication and T.30 in-band FAX communication over the IP network to positively detect a CNG signal and achieve switching to FAX reception in the answerphone connection mode and the FAX/TEL-switching mode. The communication apparatus includes a MODEM that controls facsimile communication and a SLIC that controls a telephone. A selector includes switches for connecting the IP network and the MODEM, and switches for connecting the IP network and the SLIC. A CPU controls the switches of the selector such that signals from the IP network are supplied to both of the MODEM and the SLIC.