Circuit arrangement for establishing and terminating a data connection

Claim 1

In a circuit arrangement for establishing and terminating a connection in a subscriber communication system, the arrangement including a data transmission device arranged to be connected to an associated subscriber line of the system and including a data terminal, a voice loop testing device connectable to the subscriber line, a line connection device supplied with operating voltage by the terminal, and connected to receive signals produced by the voice loop testing device, an automatic dialing device, a current supply connected to receive operating voltage from the subscriber line, a control device connected in the data transmission device and to the automatic dialing device for performing and monitoring the sequence of individual operating states of the data transmission device, and a memory unit connected to the control device for storing a representation of the present operating state of the data transmission device, the improvement wherein: the operating state representations stored in said memory unit are those required for reestablishment of an existing connection; and, said control device constitutes means responsive to a temporary interruption in the supply of operating voltage to said current supply from the subscriber line for reading out from said memory unit, after such interruption has ended, the representations stored therein and for then reestablishing the connection existing before such interruption.