Establishing data connection via telephone network - forming connections between subscribers in digital telephone network using interface CCITT-X-21 and terminal adaptors

摘要

The subscriber's appts. (DTE1, DTE2) are connected to the network (FN) via terminal adaptors (TA1, TA2) resulting in connection between the them (TA1, TA2) with the help of predetermined network signals. The first subscriber's appts. (DTE1) is coupled to the assigned first terminal adaptor (TA1) via a CCITT X.21 interface. The adaptor is coupled to the telephone network (FN) via a digital four wire interface and can be connected to a second terminal adaptor (TA2) also coupled by four wires to a two wire subscriber's appts (DTE2) via a X.21 interface. USE - Connecting subscribers of digital telephone network for data exchange.