The frequencies of cell phone scanners are essential to the operation of cell phones.

A frequency is the number of occurrences of a repetitive event per unit of time. It is most commonly thought of as a wave going from one place to another. The up and down crests of the wave as it moves forward would be the repeated occurrences. If the speed of the rising and falling crests of the wave changes, the frequency changes.

The types of ascending and descending waves used by mobile phones are essentially radio waves. Most cell phone carriers usually get 832 radio frequencies for use in a particular city. Cell phone scanner frequencies are generally used in sets of two. Every cell phone uses two frequencies per call. This is known as channel duplex. Consequently, there are typically 395 voice channels per carrier.

Therefore, each cell has about 56 available voice channels. In other words, in any given cell, cell phone scanner frequencies can have 56 people talking on their cell phones at once. These older, basic analog cellular systems are considered first-generation mobile technology, or 1G. With the introduction of digital transmission methods about 10 years ago (2G), the number of available channels increases. This was known as 2G. And now we have 3G or third generation networks. This drastically increases the number of channels.

Although the frequencies of cell phone scanners have increased, cell phones have low power transmitters. Many cell phones are less powerful than older CB radios. This has some advantages. Low power transmission means the cell phone can use smaller batteries. Also, phone call transmissions remain inside a city cell, near a cell tower. This means that the same cell phone scanner frequencies can be used again in different parts of the city.

The cellular approach requires a large number of base stations in a city of any size. A typical large city may have hundreds of cell towers. But because so many people use cell phones, the costs per user remain low. Each carrier in each city also has a central office called a Mobile Telephone Switching Office (MTSO). This office handles all telephone connections to the normal landline telephone system and controls all base stations in the region.