Communications Zone is a US Army and NATO term which describes a part of the theater of war operations

Theater (warfare)

In warfare, a theater, is defined as an area or place within which important military events occur or are progressing. The entirety of the air, land, and sea area that is or that may potentially become involved in war operations....

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The Communications Zone is the rear part of theater of operations (behind but contiguous to the combat zone) which contains the lines of communications, establishments for supply and evacuation, and other agencies required for the immediate support and maintenance of the field forces.