(DCE) The devices and connections of a communications network that connect the communication circuit between the data source and destination (the Data Terminal Equipment or DTE). A modem is the most common kind of DCE.
Before data can be transmited over a modem, the DTR (Data Terminal Ready) signal must be active. DTR tells the DCE that the DTE is ready to transmit and receive data.
DCE and DTE are usually connected by an EIA-232 serial line. It is necessary to distinguish these two types of device because their connectors must be wired differently if a "straight-through" cable (pin 1 to pin 1, pin 2 to pin 2 etc.) is to be used. DCE should have a female connector and should transmit on pin two and receive on pin three. It is a curious fact that many modems are "DTE" according to the original standard.