Device for monitoring a telephone connection of an exchange line for external extraneous connections

摘要

External extraneous connections to an exchange line (1) of a telephone connection (13) can be identified with a device which has a current sensor (5) to detect the current flowing on the exchange line (1) and a voltage sensor (2) to detect the voltage present between the conductors of the exchange line (1), and an evaluation circuit (8) which identifies as an extraneous connection a change in the voltage caused by a connection which is set up or which is to be set up and a simultaneous absence of an associated current flow on the telephone connection (1). <IMAGE>