Chapter 13: Is It a Phone or a Computer? (Or, Understanding VoIP and Convergence)

One of the newest trends in networking is the convergence of two distinct but similar types of networks: computer networks and telephone networks. Both types of networks can be either cabled or wireless, and both can carry voice and data. In other words, the distinction between computer networks and telephone networks is getting blurry.

This chapter gives you a brief introduction to VoIP, a technology that lets you send voice data over your computer network. In other words, VoIP attempts to make your phone cables obsolete by having the computer network handle voice traffic.

Tip 

This chapter isn't a complete guide to VoIP. For that, check out VoIP For Dummies, written by Timothy V. Kelly and published by Wiley.

Understanding VoIP

VoIP, which stands for Voice Over IP (Internet Protocol), works much the same as a regular telephone. However, rather than connect to the public telephone network, your phones connect directly to the Internet. The main benefit is reduced cost, especially if you make a lot of long distance phone calls. Most VoIP services charge a single flat monthly rate, usually in the neighborhood of $25–$35.

When you use a normal phone to make a long distance call, your voice is transmitted (usually in digital form) over the public switched telephone network, or PSTN. Along the way, you're charged by-the-minute fees by your long distance service provider.

When you use VoIP, your voice is still converted into digital form. However, rather than be sent over private networks owned by telephone companies, it is sent over the Internet. Because the Internet uses the IP protocol, the digital data that represents your voice must be converted into packets that can be sent reliably over IP-hence the name Voice Over IP, or VoIP.

Carrying telephone conversations over the Internet isn't new. In fact, the technology has been around for many years. Only recently has the technology become inexpensive enough to catch on for residential service. That's why you may not have heard of VoIP until now.

There are two basic approaches to setting up VoIP:

• Software-only VoIP systems: These run on your computer and enable you to talk free with anyone else anywhere in the world provided they're using the same software you are.

  The best-known software-only VoIP system is Skype (http://www.skype.com). The advantage of Skype is that it's free. Software-only VoIP has two major drawbacks:

  • You can only use it from your computer. You can't just pick up a phone, dial a number, and make a call via Skype.

  • The other person must use Skype. You can't just call anyone.

  Tip 

  A fee-based system, SkypeOut, lets you call regular phone numbers from Skype for about $0.02 per minute (way cheap).

  Skype is great if you do most of your long distance calling to geeks who don't mind sitting at the computer for "phone" calls.

• VoIP services, such as Vonage and AT&T CallVantage: These services don't require a computer. They use an Analog Telephone Adapter (ATA) that connects a normal telephone to the Internet. The adapter lets you use VoIP pretty much as though it were a regular telephone. You just pick up the phone and dial a number. The fact that the call is routed over the Internet rather than over the public phone network is, for the most part, transparent.