Circuit arrangement for the transmission of data signals between subscriber terminals operating with different data transmission procedures

A circuit for transmission of data signals between first subscriber terminals operating with a first data transmission protocol and with second subscriber terminals operating with a data transmission protocol different from the first data transmission protocol, through a data switching system with conversion of the data signals provided by the first subscriber terminals into data signals compatible with the second subscriber terminals, such that the first subscriber terminals and the second subscriber terminals are connected to separate line circuits of a first and second group of line circuits, comprising:

• at least one manual switchboard having at least one job memory unit and a control unit connected to at least one line circuit of each of said first and second groups of line circuits, such that jobs sent from the data switching system for manual switching connections and which include the selection data and the data signals from the first subscriber terminals are input to the memory unit together with a continuously assigned job number and output in the sequence in which they were input, under control of control signals provided by the control unit, such that said control unit only maintains, for each job, the selection data required for setting-up of a connection, and the data signals for a conversion and associated forwarding to the second subscriber terminal.