What does the term "Cellular" refer to in telephone communication?

The term "Cellular" in telephone communication specifically refers to small geographic areas covered by each base station. This concept is fundamental to the operation of cellular networks, which are designed to divide a larger geographic area into smaller cells. Each cell is served by its own base station, enabling efficient frequency reuse and enhancing the capacity of the network.

This cell-based architecture allows for a larger number of simultaneous calls and better management of resources, as each base station can handle communications within its designated cell while handing off calls to adjacent cells as users move. The division into smaller areas also facilitates greater coverage and better signal quality.

In contrast, the other options describe different concepts that do not accurately reflect the meaning of "Cellular" in this context. For instance, overlapping networks or all mobile devices in a region do not specifically capture the essence of cellular technology, which is focused on the segmentation of coverage areas. Similarly, international call regions pertain to a broader context not specific to how cellular systems operate.