Section 1.2. VoIP (Voice over Internet Protocol)

1.2. VoIP (Voice over Internet Protocol)

Let me say, first off, that VoIP is a terrible choice for an acronym, which degrades the technology and benefits provided. If it was called it CRAP (Conversation Remote Access Protocol), at least it would be funny and middle school boys would get a big laugh. But we're saddled with VoIP (say "toy: with an ending "p" then replace the "t" with a "v"), a graceless sound that calls to mind a love-starved Amazonian parrot's mating call.

Note: Name ChainInternet Telephony = VoIP = digital phone conversations = less dependence on the traditional telephone companies = savings and more features.

That said, let me offer you three levels of explanations: Overview, Some Details, and More Details. When you read enough details to feel comfortable that the technology works generally and will work for you specifically, skip the rest and go to something else in the book that interests you. If you want details, keep reading.

1.2.1. Minimum Requirements

There are three things you must have to use traditional phone services:

A telephone line
A phone
An account with a phone company

There are four things you must have to use Internet Telephony (I won't ever say that four-letter wordVoIPunless absolutely necessary). Here are the minimum requirements for talking over the Internet:

A broadband connection: A must-have, and don't believe the few companies who say you can use a standard telephone line and a modem. Cable and DSL broadband customers will have no problems, and are already inundated by sales pitches from their providers. Satellite broadband users must have satellite service that operates at broadband speeds both ways, and even then you shouldn't bother because you won't be happy with the delays introduced by the satellite distances.
A telephone or equivalent: You can get adapters to use a standard telephone with an Internet Telephony service. You can also use a microphone and your computer's speakers, or a headset that plugs into your computer in place of a telephone. But you need something to talk into and hear out of.
A computer: Softphone systems use special software to turn your computer into a telephone, so obviously, you need a computer. Internet Telephony services normally provide an adapter to connect your existing telephones to the Internet for calling, but you will need a computer to configure and monitor your service. Special Internet telephones have a small computer inside them, and for the services that work on handhelds (such as Skype for Pocket PC)well, your handheld is the computer.
Electrical power for the telephone: Traditional telephones are powered over the phone lines by the telephone company, but Internet telephones need power from some other source.

Note: Power ReservesOK, that last item may have given you pause. What happens if the power goes out? Watch for details in Chapter 4.

Notice what's missing? An account with any type of phone company. You can bypass that if you want, especially the part where you send them money each month. Listing yourself with a service (as you do with Skype) so others can find you is somewhat like an account with a phone company, but it's more like registering your address than subscribing.

Internet Telephony services do act more like a phone company by switching your calls and providing services, but they aren't traditional phone companies. They will charge you a monthly fee, but that fee includes far more services than you can get with a regular telephone and also reduces costs for long distance calls by a huge margin.

Note: Pick A NameSince others also avoid using the term VoIP, a variety of names have been created. Internet Telephony is a good one, as well as Broadband Phones or IP (Internet Protocol) Phones. One of these days we'll just call them phones, just as we now call cordless phones just phones.

There are a variety of other things you may want to use for added features and flexibility, but the minimum requirements are pretty minimal. Well over 30 million homes in the U.S. already have broadband, and that number is expected to reach nearly 50 million by 2009, so the market for Internet Telephony is a large one that continues to grow.

1.2.2. Basic Internet Telephony Overview

Internet Telephony converts your voice into data packets, similar to what the traditional phone company does when sending voice over fiber cables for long distances. At the far end, the data packets are converted back into sound signals and the voice you hear.

Note: Data in TransitA packet is a block of data. A block of data must almost always be broken into small pieces for easier transmission. Packet sizes are pretty small, ranging from 53 bytes up to around 1,500 bytes (in a plain, unformatted email message, a byte corresponds to a single letter, digit, or symbol) depending on the specifications of the network carrying the packets.Think of 500 tourists all going to the same cathedral. No one vehicle will carry them all, so they split up. Some may go in groups of 4 in cars and some may go in groups of 40 in buses. Data packets work the same way, but they're usually better dressed than tourists.

The main difference isn't that voice sound waves are digitized for easier transmission, but that the Internet, rather than the telephone company's network, carries the signals. But this is a big change in how voice calls, the link of one person in one place to another person in another place, are handled.

While the traditional phone system connects to a phone number attached to a physical device (desk phone, cordless phone, or cell phone), Internet Telephony can route a phone connection to a variety of network devices. This can be done because the Internet telephone call is treated like data, and can be routed to a device based on where a user is logged in. If you've used Instant Messaging from both home and work, you know that people can find you when you're logged in from either location, and have experienced this already. Table 1-2 shows some of the key differences and similarities.

Table 1-2. Telephone calls over the traditional telephone network and the Internet
Traditional telephone	Internet telephony
Dial a regular telephone	Dial a regular telephone
Connect to your central office	Connect to your Internet Service Provider
Call goes over the telephone network	Call goes over the Internet
Call connects to central office at far end	Call connects from Internet to central office on the far end
Phone rings at the far end	Phone rings at the far end

Check Chapter 2 for details about which type of Internet Telephony service will work best for you, but you can easily replicate your existing telephone experience using a broadband phone. In fact, you can completely replace your existing telephone, including services such as 911 calls, with Internet Telephony. You will get similar services for similar money, and Internet Telephony will give you more features. People can call you, and you can call anyone in the world with a phone, whether they have Internet telephone service, a cell, or an old-fashioned phone.

1.2.3. More Internet Telephony Detail

Although the process of turning analog voice streams to digital packets is similar to that already used by the telephone companies, there are differences. The traditional telephone companies are still bound by the demands of circuit switching and the need to keep a circuit continuously connected during a conversation. Using packets helps cram more phone conversations onto fiber and satellite links, but the bandwidth demands remain high. Even calls routed over high-density fiber segments require bandwidth dedicated to that individual call in order to maintain the circuit.

The bandwidth required for a traditional analog telephone call is slightly less than a megabyte per minute. Voice channels are 64 kbps (kilobits per second), meaning two of them (both sides of the conversation) require 128 kbps for the circuit.

Usually, one person listens while the other person talks, so one channel sits empty and unused. But the silent person could say something at any time, so the phone company must keep both channels of the switched circuit open (see Figure 1-4).

Figure 1-4. Wasted bandwidth in traditional phone conversations

Either your Internet-enabled telephone, software in your computer, or the adapter sitting between your regular phone and your broadband modem will convert the sound waves hitting the phone microphone into packets. Modern analog to digital conversion samples sounds at least 8,000 times per second (and sometimes more). The high sample rate possible today is one reason your Internet Telephony calls may actually sound better than your traditional phone calls.

Thirty packets per second will leave the computer when a person is speaking. Each will travel over the Internet, and they may not all travel over the same route because Internet traffic streams constantly reroute themselves to make sure they get to their destination as quickly as possible. At the far end, the packets are reassembled in order in a buffer (quickly), then played through the speaker.

Internet Telephony has the luxury of creating packets only when there's a sound, cutting the bandwidth demands in half (or almostmost reports say about 40% because we interrupt each other far too often). When one end of the phone call is quiet, smaller data packets marking the silence are sent less often.

Silence-filled packets are smaller since they contain no sound data. They do include the amount of time no sounds were digitized to keep the conversation flowing normally (see Figure 1-5). They also wait longer between packets, sending a packet every 180 milliseconds rather than every 30.

Figure 1-5. More efficient packet voice bandwidth usage over a broadband connection

For connections with limited upstream bandwidth (such as ADSL, satellite Internet, and many cable Internet services), most services offer ways to increase the compression of outbound voice traffic to use less bandwidth. The sound quality drops slightly, but the alternative is to potentially drop the conversation altogether if other upstream traffic steals too much of the limited bandwidth.

By utilizing intelligent compression and sending only sounds, telephone calls over the Internet take much less bandwidth generally than standard voice calls. How much less? Many businesses use a data connection called a T1 line (1.544 Mpbs) that supports a maximum of 24 voice calls at one time. That same T1 line can carry 173 Internet Telephony voice calls at one time with compressed, but still understandable, voice packets. This is one reason businesses now send many of their office to office phone calls over the Internet rather than over the traditional telephone network (because getting seven T1 lines worth of calls from one T1 circuit makes the accountants happy).