My introduction to the grand daddy of cell phones was while I was working as a Forest Fire Lookout man, in the early 1980s. One of my colleagues worked on a lookout tower, in radio range of a radio telephone repeater tower. So he could use a radio telephone, and free up more of the Forest Service frequency that I used. His radio telephone was about the size of a lap top. Cell phones are really down-sized radio telephones.
The advantage cell phones have today, over the old Radio telephone, is that they are much smaller and easier to use than the old radio telephones. Cell phones use very little battery power compared, to a radio telephone. This fact has helped the cell phone designers reduce their size to that of an object that can fit in your pocket.
The radio telephone was big and had to have a very powerful radio signal to reach the few radio towers that existed. The radio signal it transmitted had to be powerful enough to reach a tower 40 or 50 miles away.
Cell phones today are much smaller, and easier to use. Both people on a cell phone call can talk at once. Both listen at the same time. When using a radio telephone, only one person can talk at a time, while the other person can only listen. Since there are many cell towers in the system, many more people can use cell phones, than could use the old radio telephones. Radio telephones only had about 25 frequencies, available to use. Today each cell has about 56 voice channels available.
The cell phone system is divided into small cells, which allows greater frequency reuse in an area, so that millions of customers can use cell phones at the same time. Today modern cell phones can communicate on 1,664 frequencies or more! Each cell occupies about 10 square miles. There can be 56 people talking on their cell phone at one time within the area of a cell. The cell phone uses a much less powerful radio signal than a radio telephone. The larger number of cell phone towers makes this possible. Another advantage of using a low power radio signal of 3 watts is that it fades to near nothing past the edge of the cell; so the same frequencies can be reused in the neighbouring cells. As you travel you are switched automatically from the cell tower you are moving away from to the next best located tower in the area you are going toward. As you travel your cell phone sends out a code signal which identifies itself, you the user, and the service provider. Your cell phone is always communicating with the cell tower and its service provider. This is done to keep track of which cell it is located in, how strong the signal strength is received, and transmitted, and to determine if the cell you are in, is owned by your provider, or another company. A person can travel for hundreds of miles and hold a conversation the entire time using cellular technology.