| 摘要 |
A subscriber station (1) functioning as a concentrator is connected to subscribers (3) and is connected via trunk lines (4) to a centrally placed transit exchange (5) establishing connections, by reason of a given command, between a source (8) sending special information and a trunk line pointed out as being idle. The subscriber station includes a trunk line economizing apparatus (15-29) investigating each time a subscriber calls the source whether one of the trunk lines is already connected to the source. If no such connection is determined, the source and the calling subscriber are conventionally connected to a trunk line pointed out as being idle, the number of this line being intermediately stored in a memory unit (20) associated with the economizing apparatus. If it is determined at the investigation that the special information is already being transferred to the subscriber station, the subscriber calling the source is connected to the trunk line whose number is intermediately stored in the memory unit. The economizing apparatus includes a circuit (27) for cancelling the intermediate storage when the special information is no longer received by any of the subscribers. Independent of the number of subscribers receiving the special information, only a single trunk line is taken into use, and the central transit exchange is only loaded with a single connection establishment. |
