Power source system for data terminal equipment

摘要

A power source control system is disclosed for a data terminal which is connected to a communication line through a modem and a network control unit. A power source control unit is provided between the modem and the data terminal while interface between the modem and the data terminal is maintained so that when an incoming call to the data terminal is received and detected, a line establishing procedure is immediately executed with resepct to the calling party in place of the data terminal, and a main power source of the data terminal is turned ON, making the data terminal ready for a communication operation.