Method for identifying the answering signal of a called subscriber in telecommunications switching systems, in particular telephone switching systems

摘要

The invention relates to a method for identifying the closure of the subscriber loop as a result of a ringing signal for the purpose of ring tripping for telecommunications systems, in particular telephone systems. If, as a result of a ringing signal, the subscriber answers, for example, by lifting the receiver, a current comprising the ringing current and/or the feed current then flows via the speech circuit or power supply of the subscriber terminal TE. In the ringing phase, a ringing signal reception component RE in the subscriber terminal TE causes a phase shift of the AC ringing current IR in relation to the ringing voltage UR. When the subscriber answers, the phase shift is cancelled by the ohmic response of the subscriber terminal TE and evaluated as an off-hook answering signal. <IMAGE>