A cell phone is similar to a radio. "Walkie-talkies" and "citizens band" radios were early forms of cell phones, but their reach was limited and they did not provide privacy. A cell phone, unlike a walkie-talkie, uses different radio frequencies for both speakers which enables two people to talk and listen at the same time.

Radio-telephones in cars became available after World War II. However, as a result of the expensive costs, bulky hardware and a limited reception reach of about 50 miles, the benefits of owning a radio-telephone did not outweigh the costs.

Modern wireless carriers have broken their transmission capabilities into cells, each with a base station and transmission tower. Different cells can use the same frequencies, which allows users to move from cell to cell while carrying on a conversation.

When calling someone on your cell phone, the number you dial triggers a radio search for that phone; an automated controller selects frequencies, and contact is established. Maintaining contact is harder if you're moving from cell to cell: this is why "roaming charges" are part of some service plans.

Modern cell phones use less power than early models and their batteries have gained capacity. Today's cell phones require small batteries, which enables the phones to be small and portable.

Using a cell phone used to be expensive because few people had them, and they had to pay for the transmission service. Now, the cost is shared by millions of people, which makes the cost of owning a cell phone much less expensive.