Mobile phones are called "cell phones" because their networks are divided into a grid of hexagonal areas known as cells.

The concept of the cellular network was first proposed by researchers at Bell Labs in 1947, specifically by engineers Douglas H. Ring and W. Rae Young. They envisioned a system of low-power transmitters that could reuse frequencies in non-adjacent areas to increase network capacity. This was a revolutionary departure from the high-power, single-transmitter systems used for early mobile radio services, which could only support a handful of calls at once.Hexagons are the preferred geometric shape for these cells because they are the closest regular polygon to a circle that can tile a plane without gaps or overlaps. While a circle would be ideal for uniform signal propagation, circles cannot be tiled together without creating dead zones. Hexagons provide the most efficient coverage area for a single antenna while ensuring that every point in the grid is serviced by a nearby tower.The first commercial cellular network was launched by NTT in Tokyo in 1979, followed by the Ameritech system in Chicago in 1983. Modern systems rely on a process called a 'handoff' or 'handover,' which occurs when the signal strength from a neighboring cell exceeds that of the current cell. This transition is managed by a Mobile Switching Center (MSC) that coordinates the timing to ensure the user experiences no interruption in service. This spatial frequency reuse is what allows modern providers to support billions of devices globally.