Telecommunications terminal with dial blocking circuit improved for dial blocking taking account of certain requirements, e.g. for evaluation circuit to satisfy impedance requirements

摘要

The terminal has an evaluation circuit (AWS) designed to provide a signal to a dial blocking circuit (WSS) to produce a blocking signal depending on the amplitude of a sensing resistance (RSP, RSC) between the a- or b- wire (AAD, BAD) and a sensing wire (FAD). The evaluation circuit has a controlled current source (SQP, SQN) whose current is determined by the sensing resistance and a threshold circuit (KOM) designed to output the signal to the dial blocking circuit if a predefined current limit is exceeded