DTE

Data terminal equipment (DTE) is a term or concept initially developed by IBM to refer to any device that converts information into signals for transmission purposes, or converts received signals to information. In other word, it is a device that is the source or sink of information. Although the term has been applied to multiple layers in the OSI Reference Model (OSI-RM), it is most commonly associated with the Physical Layer and associated with bit transmission.

Although it is possible for two DTE to be directly connected using a null modem cable, the term DTE is most commonly associated with data circuit-terminating equipment (DCE), and a DTE is typically connected to a DCE. The DCE is typically responsible for providing clocking for synchronization purposes, which introduces another defining characteristic of DTE: they typically are not capable of generating a clock signal.

There are many examples of equipment that would be considered DTE. In the age when communication with a minicomputer or mainframe was accomplished using a dumb terminal, the terminal was the DTE on the circuit connecting it to the computer or a terminal server or cluster controller. A computer with terminal emulation software and using the serial interface built into most computers can also be a DTE. Other examples of DTE include:
A computer connected to a modem that it is using for dial access to a network resource (e.g., the Internet)
A router connected to a DSU through which it is connected to a private line, or packet network service
A router or computer connected to an ISDN NT1 through which it is connected to a network resource (e.g., the Internet)