Asking yourself, "How does a mobile phone work?" You don't really need to know how it all works to use one, of course, but if you're curious, keep reading. They're similar to two-way radios, so if you're familiar with those, you may feel right at home understanding the workings of a cell phone. However, instead of only working on one or even thirty-five channels, a cell phone can work on well over 1,000, which is why so many people can talk on cell phones simultaneously without a problem.
So How Does a Mobile Phone Work
Whether you're on a GSM or CDMA system, here is the basic sequence of events:
- You talk into your cell phone.
- Your voice is turned into radio waves.
- Those radio waves reach a local base station, then they are sent to the base station close to the recipient of the call. Base stations are allotted for the small regions in a cell phone company's coverage map. These areas are called "cells."
- The base station transmits the call to the recipient's phone. Base stations are made up of transmission dishes, antennae, and an electrical cable that connects to the cabin that holds the equipment. The dishes transmit microwave rays far above the ground, connecting one base station to the next.
- Those radio waves are converted back into "voice" and you and the recipient can have your conversation.
So how does the signal know which phone to go to? There's a microchip, called a SIM card (Subscriber Identification Module) in the back underneath the battery. It holds all of the phone's information and when a signal is sent out for that particular card or user, the SIM picks it up. This is for a GSM network. CDMA networks operate similarly.
It doesn't even matter if you're on the move because your phone can communicate with more than one base station as you drive. They overlap, allowing you to continue your call without a drop in signal as long as you're within the cell phone company's coverage area. While you talk, the base stations automatically adjust to use the smallest amount of power possible. Because of this, frequencies can be reused by base stations that are not side-by-side.
Cell phones get their power from rechargeable batteries. They're often lithium ion batteries, but there is a shift toward lithium-polymer batteries thanks to their negligible weight and ability to come in different shapes to accommodate the different phone styles. The batteries can be small and lightweight because cell phones don't need a lot of power to run.
When You Turn on the Phone
Right when you turn your cell phone on, it starts working. If you get a "No Service" message, chances are you're out of range of your carrier.
In addition, the phone will send out an MTSO, which is a code that allows the cell phone network to know which cell you're in when someone tries to call you. Your phone is tracked while it's on and updated in a database.
When Someone Calls
Once the MTSO determines where you are, it has to decide how to connect you to the person who is calling you. It chooses the best frequency for the call to take place. If you are traveling as you talk, the MTSO sets up a "hand-off" to a new cell, working with two base stations to establish your new spot on the map. If, while you're driving, you end up in another cell phone carrier's cell, you won't necessarily drop the call (though in some cases, you can set your phone to drop the call rather than go into roaming mode). You could be charged outrageous fees for this, so be aware. Study the map you get when you purchase your phone to know where you can and cannot talk on your cell phone company's towers.
A Final Word
Asking, "How does a mobile phone work?" could get you anything from shrugs to a launch into unfamiliar territory with much more intricate details than you wanted. However, the overall process is relatively simple. It's all about coding (in your phone and that of the cell phone service provider), base stations with transmitting dishes, and the ability for those systems to track which cell each phone is in while it's on.