A Simple version of how a Cell phone works

A Cell phone is a digital version of a Radio Telephone. Then you ad GPS satellites and microwave relay stations.

So, let's imagine someone makes a call from a land line to a cell phone. This phone call travels down the line until it reaches a Cell phone microwave towers (there are thousands to million of  them all over the world. These are much easier to install than long land line phones by the way worldwide. So, this saved billions of dollars (this aspect of moving from land lines to Cell towers by the way).

Because GPS (Global Positioning Satellites) can track any device set up for this within about 3 to 6 feet of any location on earth, when your cell phone is on it is "Pinging" with the nearest cell tower. Now I'm going to make up an unreal cell number within the U.S. it is "222-222-2222". This is how many digits you need to call anywhere in the 50 states of the U.S.

So, your cell phone is saying to the nearest Microwave relay tower at least once every 30 seconds to 1 minute (Hey I'm here in this area, I'm  "222-222-2222" if a call comes for me so I can ring and take a message (even though messages might be kept off of cell phones on a mainframe computer some where in the U.S. or out of country as well and the same for text messages and other stuff). So, then from somewhere else on earth someone is trying to call  "222-222-2222" and then your cell phone rings. Or you make a call from  "222-222-2222" to "333-333-3333" somewhere on the east coast of the U.S. from say San Francisco. Then your phone says to the nearest Microwave tower (Find "333-333-3333") wherever it is in the U.S. because of the way this number was dialed). So if it finds "333-333-3333" then that cell phone rings on the east coast.

Sometimes when you use a dial sequence like this your phone might ring overseas too. So, if you don't have a plan for this you might want to let the phone company know that you won't accept phone calls when you leave the 50 states of the U.S. Even in Hawaii and Alaska this system works by the way. So, basically you can call for free anywhere in the 50 states and talk for as long as you want to  (as long as you have a plan that lets you do this for a set monthly fee).

If you forget to do this just don't answer your phone to reduce any charges that might occur if you don't have a plan set up for sending or receiving overseas calls from the U.S. But, IPhones are generally speaking "international phones" but just remember not all cell phones can make international calls so if you want this feature be sure to ask for it when you buy your cell phone.

However, if you have a phone that doesn't receive international calls that might save you money when people accidentally call your from overseas too whether you know them or not. It's all up to you what you want to do here.