Back channel and Communication channel

Back channel noun - An alternative to the regular channels of communication that is used when agreements must be made secretly (especially in diplomacy or government).

Communication channel and back channel are semantically related. In some cases you can use "Communication channel" instead a noun phrase "Back channel".

Communication channel noun - (often plural) a means of communication or access.

Back channel and communication channel are semantically related. Sometimes you can replace phrase "Back channel" with "Communication channel", this phrases are similar.