Prior to the initialization, CPU of information processing equipment makes a decision about whether a communication line has been connected to a connector or not. When the two are connected, the CPU does not carry out the initialization and shifts xDSL modem to lower power consumption mode. The connection is checked as follows. A test signal is transmitted through the xDSL modem. This signal is reflected by the connector and reflection is received by hybrid circuit. When the energy of this echo is large it means that the communication line it not connected to the connector, when the energy is small it means that the two are connected.