How WiFi Phones Work

Free stuff is good, and free stuff that you'd ordinarily have to pay for is even better. That's one of the reasons people have tried using Voice over Internet Protocol (VoIP) to make phone calls. With VoIP, you can make calls, even long-distance and international ones, for free. But until recently, VoIP had one pretty big limitation -- to make a call, you had to be at a computer.

New phones make it possible for people to place VoIP calls without being leashed to a computer. WiFi phones use the same wireless network technology that computers use, making VoIP a lot more portable.

This article will explore WiFi phones and their abilities, as well as the pros and cons of using them. We'll start with a quick review of VoIP and WiFi.

WiFi & Telephone Basics

Understanding VoIP is easier if you have a basic understanding of how old-fashioned telephones work. Most people have used an ordinary "land line" phone so often that the process seems instinctive. You just pick up the phone, hear a dial tone, dial, talk and hang up.

But several things happen between you dialing the phone and the other person answering. To get from person to person, the call travels through the wires that make up the public switched telephone network (PSTN). Your local phone carrier routes your call through a series of physical switches that eventually connect your phone to the other person's. This is called circuit switching.

Wi-fi phones are part of the smartphone phenomenon. Click here to read more about smartphones.

VoIP, on the other hand, uses packet switching. We'll look at packet switching and VoIP in more detail next.

How Bluetooth Works

There are lots of different ways that electronic devices can connect to one another. For example:

• Component cables
• Electrical wires
• Ethernet cables
• WiFi
• Infrared signals

When you use computers, entertainment systems or telephones, the various pieces and parts of the systems make up a community of electronic devices. These devices communicate with each other using a variety of wires, cables, radio signals and infrared light beams, and an even greater variety of connectors, plugs and protocols.

The art of connecting things is becoming more and more complex every day. In this article, we will look at a method of connecting devices, called Bluetooth, that can streamline the process. A Bluetooth connection is wireless and automatic, and it has a number of interesting features that can simplify our daily lives.

The Problem

When any two devices need to talk to each other, they have to agree on a number of points before the conversation can begin. The first point of agreement is physical: Will they talk over wires, or through some form of wireless signals? If they use wires, how many are required -- one, two, eight, 25? Once the physical attributes are decided, several more questions arise:

• How much data will be sent at a time? For instance, serial ports send data 1 bit at a time, while parallel ports send several bits at once.

• How will they speak to each other? All of the parties in an electronic discussion need to know what the bits mean and whether the message they receive is the same message that was sent. This means developing a set of commands and responses known as a protocol.

Why is it called Bluetooth?

Harald Bluetooth was king of Denmark in the late 900s. He managed to unite Denmark and part of Norway into a single kingdom then introduced Christianity into Denmark. He left a large monument, the Jelling rune stone, in memory of his parents. He was killed in 986 during a battle with his son, Svend Forkbeard. Choosing this name for the standard indicates how important companies from the Nordic region (nations including Denmark, Sweden, Norway and Finland) are to the communications industry, even if it says little about the way the technology works.

How Cell Phones Work

Millions of people in the United States and around the world use cellular phones. They are such great gadgets -- with a cell phone, you can talk to anyone on the planet from just about anywhere!

These days, cell phones provide an incredible array of functions, and new ones are being added at a breakneck pace. Depending on the cell-phone model, you can:

• Store contact information
• Make task or to-do lists
• Keep track of appointments and set reminders
• Use the built-in calculator for simple math
• Send or receive e-mail
• Get information (news, entertainment, stock quotes) from the Internet
• Play games
• Watch TV
• Send text messages
• Integrate other devices such as PDAs, MP3 players and GPS receivers

But have you ever wondered how a cell phone works? What makes it different from a regular phone? What do all those terms like PCS, GSM, CDMA and TDMA mean? In this article, we will discuss the technology behind cell phones so that you can see how amazing they really are. If you are thinking about buying a cell phone, be sure to check out How Buying a Cell Phone Works to learn what you should know before making a purchase.

To start with, one of the most interesting things about a cell phone is that it is actually a radio -- an extremely sophisticated radio, but a radio nonetheless. The telephone was invented by Alexander Graham Bell in 1876, and wireless communication can trace its roots to the invention of the radio by Nikolai Tesla in the 1880s (formally presented in 1894 by a young Italian named Guglielmo Marconi). It was only natural that these two great technologies would eventually be combined.

How Digital Cameras Work

In­ the past twenty years, most of the major technological breakthroughs in consumer electronics have really been part of one larger breakthrough. When you get down to it, CDs, DVDs, HDTV, MP3s and DVRs are all built around the same basic process: converting conventional analog information (represented by a fluctuating wave) into digital information (represented by ones and zeros, or bits). This fundamental shift in technology totally changed how we handle visual and audio information -- it completely redefined what is possible.

The digital camera is one of ­the most remarkable instances of this shift because it is so truly different from its predecessor. Conventional cameras depend entirely on chemical and mechanical processes -- you don't even need electricity to operate them. On the other h­and, all digital cameras have a built-in computer, and all of them record images electronically.

The new approach has been enormously successful. Since film still provides better picture quality, digital cameras have not completely replaced conventional cameras. But, as digital imaging technology has improved, digital cameras have rapidly become more popular.

In this article, we'll find out exactly what's going on inside these amazing digital-age devices.

Understanding the Basics
Let's say you want to take a picture and e-mail it to a friend. To do this, you need the image to be represented in the language that computers recognize -- bits and bytes. Essentially, a digital image is just a long string of 1s and 0s that represent all the tiny colored dots -- or pixels -- that collectively make up the image. (For information on sampling and digital representations of data, see this explanation of the digitization of sound waves. Digitizing light waves works in a similar way.)

If you want to get a picture into this form, you have two options:

• You can take a photograph using a conventional film camera, process the film chemically, print it onto photographic paper and then use a digital scanner to sample the print (record the pattern of light as a series of pixel values).

• You can directly sample the original light that bounces off your subject, immediately breaking that light pattern down into a series of pixel values -- in other words, you can use a digital camera.

At its most basic level, this is all there is to a digital camera. Just like a conventional camera, it has a series of lenses that focus light to create an image of a scene. But instead of focusing this light onto a piece of film, it focuses it onto a semiconductor device that records light electronically. A computer then breaks this electronic information down into digital data. All the fun and interesting features of digital cameras come as a direct result of this process.

In the next few sections, we'll find out exactly how the camera does all this.

Cool Facts

• With a 3-megapixel camera, you can take a higher-resolution picture than most computer monitors can display.

• You can use your Web browser to view digital pictures taken using the JPEG format.

• The first consumer-oriented digital cameras were sold by Kodak and Apple in 1994.

• In 1998, Sony inadvertently sold more than 700,000 camcorders with a limited ability to see through clothes.

WWW versus Internet

Internet vs. World Wide Web

To answer this question, let's look at each element. And since the Internet seems to be the more easily understood component, let's start there.

Cristian Baitg/Photographer's Choice RR/Getty Images
The Internet may be the physical connection, but the World Wide Web is what really gets you tapped in.

Simply, the Internet is a network of networks -- and there are all kinds of networks in all kinds of sizes. You may have a computer network at your work, at your school or even one at your house. These networks are often connected to each other in different configurations, which is how you get groupings such as local area networks (LANs) and regional networks. Your cell phone is also on a network that is considered part of the Internet, as are many of your other electronic devices. And all these separate networks -- added together -- are what constitute the Internet. Even satellites are connected to the Internet. To learn more about how this interwoven mega-network operates, check out How Internet Infrastructure Works.

The World Wide Web, on the other hand, is the system we use to access the Internet. The Web isn't the only system out there, but it's the most popular and widely used. (Examples of ways to access the Internet without using HTTP include e-mail and instant messaging.) As mentioned on the previous page, the World Wide Web makes use of hypertext to access the various forms of information available on the world's different networks. This allows people all over the world to share knowledge and opinions. We typically access the Web through browsers, like Internet Explorer and Mozilla Firefox. By using browsers like these, you can visit various Web sites and view other online content.

So another way to think about it is to say the Internet is composed of the machines, hardware and data; and the World Wide Web is what brings this technology to life.

Now that we know the difference between the Internet and the World Wide Web, put your newfound knowledge of hyperlinks, HTML and home pages to use and click onto the next page for more great information.

Internet Innovators

There are several groups of people who work to keep everything standardized and running smoothly across the Internet and the World Wide Web. If you want to learn more about what it takes to keep systems compatible, a good place to start is the World Wide Web Consortium (W3C). W3C's aim is to help develop standards and guidelines for the Web. The group is run by Tim Berners-Lee who, if you remember, is the person who invented the World Wide Web. You can also try the Internet Society, which was founded in 1992 to provide leadership in many aspects of Internet-related information, initiatives and activities.