Circuit arrangement for signalling defective exchange circuits, which cannot be used by incoming calls, in telephone exchanges, especially telephone private branch exchanges

摘要

The invention relates to a circuit arrangement for signalling defective exchange circuits, which cannot be used by incoming calls, in telephone exchanges, especially telephone private branch exchanges. According to the invention, a statistical investigation of the incoming successful allocations is carried out, it being assumed that at least one exchange call would have to occur per exchange circuit in a predetermined time period. If this is not the case, it is assumed that one of the existing exchange circuits is defective. IMAGE