Data terminal equipment (DTE) is an end instrument that converts user information into signals for transmission or reconverts received signals into user information. A DTE device communicates with the data circuit-terminating equipment (DCE). The DTE/DCE classification was introduced by IBM.
A DTE is the functional unit of a data station that serves as a data source or a data sink and provides for the data communication control function to be performed in accordance with link protocol.
The data terminal equipment may be a single piece of equipment or an interconnected subsystem of multiple pieces of equipment that perform all the required functions necessary to permit users to communicate. A user interacts with the DTE (e.g. through a human-machine interface), or the DTE may be the user.
Usually, the DTE device is the terminal (or a computer emulating a terminal), and the DCE is a modem.
DTE is usually a male connector and DCE is a female connector.
A general rule is that DCE devices provide the clock signal (internal clocking) and the DTE device synchronizes on the provided clock (external clocking). D-sub connectors follow another rule for pin assignment. DTE devices usually transmit on pin connector number 2 and receive on pin connector number 3. DCE devices are just the opposite: pin connector number 2 receives and pin connector number 3 transmits the signals.
This term is also generally used in the Telco context to designate any device unable to generate clock signs, hence a PC to PC ethernet connection can also be called a DTE to DTE communication. This communication is done via an Ethernet crossover cable as opposed to a PC to DCE (hub, switch, or bridge) communication which is done via an Ethernet straight cable.
Reference:
http://en.wikipedia.org/wiki/Data_terminal_equipment
