Method for exchanging switching signals between telephone switching systems connected together as master and satellite stations, particularly private branch exchanges

摘要

In the exchange of switching signals, carried out by means of modems, between telephone switching systems connected together as master and satellite stations, particularly private branch exchanges, the exchange of switching signals is initiated differently depending on the state of the connection. In the idle state, a begin-to-send signal is applied directly to the line at the beginning of the exchange of switching signals, which determines the direction of transmission. This is followed by a datablock producing the readiness to receive switching signals, the structure of which does not have any information content and is designed in such a manner that no simulation by voice is possible. In the call state, the answer signal is preceded by a 50-Hz signal resulting in the connection of the modem. This measure is used for eliminating false simulation of information initiating an exchange of switching signals. The data blocks sent after that contain special data words which specify the manner in which the remainder of the data block is divided up and which type of switching information is contained in the further data words. In addition, the number of data words or the number of data blocks overall which constitute an identical information can be specified in a data word.