research process of open lines of communication in a telecommunication network

摘要

1309319 Automatic exchange systems SIEMENS AG 28 Sept 1970 [30 Sept 1969] 46013/70 Heading H4K In a telecommunication exchange network of the non-hierarchical type each exchange stores the numbers of those subscribers to which it is connected and when a call is originated from a subscriber of one exchange, the number of the called subscriber is stored in that exchange for a predetermined time during which the wanted subscriber number is compared with the stored numbers of subscribers connected to that exchange and if no match is found forwarded to adjacent exchanges which store that number and/or the number of the calling subscriber, together with the identity of the inter-exchange link over which the number was received and effect similar comparisons, the number being forwarded over different inter exchange routes until a comparison results in a match indicating that the destination exchange has been reached. If the called station is idle the number of the called subscriber is returned to the originating exchange as an acknowledgement signal over the first inter exchange path found or subsequently found path using the stored link data and when this number is received at the originating exchange the path is switched through and if the number of the called subscriber is still stored in the originating exchange the calling subscriber is connected to the switched through path. Each exchange has provision to erase stored information which is not used within a predetermined time. The originating exchange may make a second attempt if an acknowledgement is not returned within a predetermined time.