- Simplex – In simplex mode, the communication is uni-directional as a one-way street for e.g. keyboard and traditional monitors are examples of simplex devices. Keyboard can only introduce input and the monitor only accepts output.
- Half Duplex – In half duplex mode, each station can both transmit and receive, but not at the same time when one device is sending the other can only receive and vice-versa. For example: Walkie-Talkie
- Full Duplex – In full duplex mode both the stations can transmit and receive simultaneously. The signals going in one direction share the capacity of the link with signals going in other direction. Thus sharing can occur in two ways either the link must contain two physically separate transmission paths, one for sending and other for receiving. The capacity of the channel is divided between signals traveling in both directions. For example: Telephone Network.