Note 1 to entry: The channel capacity and the transmission rate of the associated transmission channels between the two points are not necessarily the same in the two directions.

Note 2 to entry: The term "bidirectional" should not be used to describe the direction of call set-ups (which is described by the term "both-way").

Note 3 to entry: In French, the terms "bilatéral" and "bidirectionnel" should not be confused with the term "duplex".