A communication device that combines transmissions from several I/O device into one line is a:
A communication device that combines transmissions from several I/O device into one line is a Multiplexer
A communication device is a hardware device capable of transmitting an analog or digital signal over the telephone, other communication wire, or wirelessly. ... Other examples of communication devices include a network interface card (NIC), Wi-Fi devices, and an access point.
A Multiplexer is a device used to communicate by means of a medium with combination of multiple signals. A DE multiplexer is a process of separating multiplexed signals from transmission line. An electronic multiplexer is a multiple-input, single-output switch. MUX allows many signals to share one device.
Alternatively referred to as an IO device, an input/output device is any hardware used by a human operator or other systems to communicate with a computer. As the name suggests, input/output devices are capable of sending data (output) to a computer and receiving data from a computer (input).