Some VoIP providers offer their services for free, normally only for calls to other subscribers to the service. Your VoIP provider may permit you to select an area code different from the area in which you live. This means you may not incur long distance charges if you call a number in your area code regardless of geography. It also means that people who call you may incur long distance charges depending on their area code and service.

Some VoIP providers charge for a long distance call to a number outside your calling area, similar to existing, traditional wireline telephone service. Other VoIP providers permit you to call anywhere at a flat rate for a fixed number of minutes.

If I have Internet Voice service, who can I call?
Depending upon your service, you might be limited only to other subscribers to the service, or you may be able to call any phone number, anywhere in the world. The call can be made to a local number, a mobile phone, to a long distance number, or an international number. You may even utilize the service to speak with more than one person at a time. The person you are calling does not need any special equipment, just a phone.

What Are Some Advantages of Internet Voice?
Because Internet Voice is digital, it may offer features and services that are not available with a traditional phone. If you have a broadband internet connection, you need not maintain and pay the additional cost for a line just to make telephone calls.

With many Internet Voice plans you can talk for as long as you want with any person in the world (the requirement is that the other person has an Internet connection). You can also talk with many people at the same time without any additional cost.

What Are Some disadvantages of Internet Voice?
If you're considering replacing your traditional telephone service with Internet Voice, there are some possible differences:

• Some Internet Voice services don't work during power outages and the service provider may not offer backup power;

• It may be difficult for some Internet Voice services to seamlessly connect with the 911 dispatch center or identify the location of Internet Voice 911 callers; or

• They may or may not offer white page listings.

The FCC has organized an FCC Internet Policy Working Group to identify, evaluate and address policy issues that will arise as telecommunications services move to Internet-based platforms. For more information on the Working Group, please visit www.fcc.gov/ipwg

Aspects of these considerations may change with new developments in internet technology.  You should always check with the VoIP service provider you choose to confirm any advantages and limitations to their service.

For more information about Internet Voice/VoIP see our factsheet. (pdf file)

* 2:00 A.M. - 5:00 P.M. Eastern Standard Time
   Tehese plans are not available in Canada but serve as an example of how the FAP is applied

VoIP is the process of sending sound or voice over the internet. In a typical call using the current technology, the voice starts as an analog signal. When the sound reaches the transmitter in the phone, the vibrations are turned into electrical impulses. The impulses are transmitted over a pair of wires to the central office switch. The switch processes the electrical impulses into digital information. This process is known as Analog to Digital or Digital to Analog (A to D / D to A). This digital signal is transmitted to a distant switch over a connection called a trunk circuit. The main function of a telephone switch is to connect the callers phone to the called party phone and convert analog signals to digital information. The network of switches used every day in the United States is known as the Public Switched Telephone Network (PSTN).

There are two sides to a switch, first is the line side connection which is a two-wire circuit that connects the phone to the switch. This connection is normally an analog link between the switch and the central office (the name of the building where the switch is located). Second is the trunk side of the switch. This connection is normally four-wire in nature and in most cases a digital link. The four-wire circuit is a full duplex circuit where there is a dedicated transmission path in both directions. Switches have many dedicated trunk groups that connect the PSTN together in a spider web fashion.

VoIP is the next generation of telephone technology. Major portions of the network are being replaced. The traditional switch has been replaced with a device known as a Gateway Controller. The GC provides an A to D function as well as placing voice packets into the IP network for delivery to a distant GC. Unlike the PSTN where switches use dedicated trunks, the VoIP network uses a shotgun approach to deliver packets to the far end.

The theory is much the same in the VoIP and traditional PSTN. The difference is in the method used to establish a call. The PSTN uses multiple switches to connect a caller in Chicago to someone in LA. In this example, let's say there are five switches in the path between Chicago and LA. Each switch in the path uses trunks that are dedicated between each switch. Switch one has trunks connecting to switch two and switch two is connected to switch three with dedicated trunks and so on and so on. The PSTN uses phone numbers as the routing key to determine the next step in the switching sequence. As a call arrives at the next switch in the path, that switch queries its database to determine the trunk group to use for routing the call to the distant end. A call making its way across the nation hops from switch to switch in what appears to be a helter-skelter fashion. The important factor in this scenario is that for each switch pair involved there is a dedicated trunk circuit locked up for the duration of the call. If there are two calls between two switches then there are two trunks in use for the length of each call.

In the VoIP network there are still switches in the network, however; the switches are packet switches moving small packets of data from point to point. The trunks have been replaced with data links that are used to deliver packets where circuit dedication is not required. Gateway Controllers break the voice into small packets of information much the same as a switch in the PSTN. The GC also starts the routing function by routing packets to a distant IP address rather than routing on a phone number. The call setup information, as well as the voice packets, hop through the IP network in a ping-pong fashion much like the PSTN without dedicating a circuit per call. Packets containing voice information are mixed with data packets containing a web page or an e-mail in route to the IP address assigned.

One thing that begins to come clear in the VoIP network is the cost of call delivery. In the PSTN each call requires a dedicated circuit and is not available for any other use during a call. The VoIP network uses circuits in small bits at a time, that is a phone call shares available circuits with anything else that needs to be transmitted without the costly locked up circuits.

• ATA - The simplest and most common way is through the use of a device called an ATA (analog telephone adaptor). The ATA allows you to connect a standard phone to your computer or your Internet connection for use with VoIP. The ATA is an analog-to-digital converter. It takes the analog signal from your traditional phone and converts it into digital data for transmission over the Internet. Providers like Vonage and AT&T CallVantage are bundling ATAs free with their service. You simply crack the ATA out of the box, plug the cable from your phone that would normally go in the wall socket into the ATA, and you're ready to make VoIP calls. Some ATAs may ship with additional software that is loaded onto the host computer to configure it; but in any case, it is a very straightforward setup.
• IP Phones - These specialized phones look just like normal phones with a handset, cradle and buttons. But instead of having the standard RJ-11 phone connectors, IP phones have an RJ-45 Ethernet connector. IP phones connect directly to your router and have all the hardware and software necessary right onboard to handle the IP call. Soon, Wi-Fi IP phones will be available, allowing subscribing callers to make VoIP calls from any Wi-Fi hot spot.
• Computer-to-computer - This is certainly the easiest way to use VoIP. You don't even have to pay for long-distance calls. There are several companies offering free or very low-cost software that you can use for this type of VoIP. All you need is the software, a microphone, speakers, a sound card and an Internet connection, preferably a fast one like you would get through a cable or DSL modem. Except for your normal monthly ISP fee, there is usually no charge for computer-to-computer calls, no matter the distance.

But chances are good you are already making VoIP calls any time you place a long-distance call. Phone companies use VoIP to streamline their networks. By routing thousands of phone calls through a circuit switch and into an IP gateway, they can seriously reduce the bandwidth they're using for the long haul. Once the call is received by a gateway on the other side of the call, it is decompressed, reassembled and routed to a local circuit switch.

Although it will take some time, you can be sure that eventually all of the current circuit-switched networks will be replaced with packet-switching technology (more on packet switching and circuit switching later). IP telephony just makes sense, in terms of both economics and infrastructure requirements. More and more businesses are installing VoIP systems, and the technology will continue to grow in popularity as it makes its way into our homes.

Flexibility
With VoIP, you can make a call from anywhere you have broadband connectivity. Since the IP phones or ATAs broadcast their info over the Internet, they can be administered by the provider anywhere there is a connection. So business travelers can take their phones or ATAs with them on trips and always have access to their home phone. Another alternative is the softphone. A softphone is client software that loads the VoIP service onto your desktop or laptop. The Vonage softphone has an interface on your screen that looks like a traditional telephone. As long as you have a headset/microphone, you can place calls from your laptop anywhere in the broadband-connected world.

Price
Most VoIP companies are offering minute-rate plans structured like cell phone bills for as little as $15 per month. On the higher end, some offer unlimited plans for $79. With the elimination of unregulated charges and the suite of free features that are included with these plans, it can be quite a savings.

Most VoIP companies provide the features that normal phone companies charge extra for when they are added to your service plan. VoIP includes:

• Caller ID
• Call waiting
• Call transfer
• Repeat dial
• Return call
• Three-way calling

• Forward the call to a particular number
• Send the call directly to voicemail
• Give the caller a busy signal
• Play a "not-in-service" message
• Send the caller to a funny rejection hotline

Now that we've looked at VoIP in a general sense, let's look more closely at the components that make the system work. In order to understand how VoIP really works and why it's an improvement over the traditional phone system, it helps to first understand how a traditional phone system works.

Circuit switching is a very basic concept that has been used by telephone networks for more than 100 years. When a call is made between two parties, the connection is maintained for the duration of the call. Because you are connecting two points in both directions, the connection is called a circuit. This is the foundation of the Public Switched Telephone Network (PSTN).

Here's how a typical telephone call works:

1. You pick up the receiver and listen for a dial tone. This lets you know that you have a connection to the local office of your telephone carrier.
2. You dial the number of the party you wish to talk to.
3. The call is routed through the switch at your local carrier to the party you are calling.
4. A connection is made between your telephone and the other party's line using several interconnected switches along the way.
5. The phone at the other end rings, and someone answers the call.
6. The connection opens the circuit.
7. You talk for a period of time and then hang up the receiver.
8. When you hang up, the circuit is closed, freeing your line and all the lines in between.

Telephone conversations over today's traditional phone network are somewhat more efficient and they cost a lot less. Your voice is digitized, and your voice along with thousands of others can be combined onto a single fiber optic cable for much of the journey (there's still a dedicated piece of copper wire going into your house, though). These calls are transmitted at a fixed rate of 64 kilobits per second (Kbps) in each direction, for a total transmission rate of 128 Kbps. Since there are 8 kilobits (Kb) in a kilobyte (KB), this translates to a transmission of 16 KB each second the circuit is open, and 960 KB every minute it's open. So in a 10-minute conversation, the total transmission is 9,600 KB, which is roughly equal to 10 megabytes (check out How Bits and Bytes Work to learn about these conversions). If you look at a typical phone conversation, much of this transmitted data is wasted.

While you are talking, the other party is listening, which means that only half of the connection is in use at any given time. Based on that, we can surmise that we could cut the file in half, down to about 4.7 MB, for efficiency. Plus, a significant amount of the time in most conversations is dead air -- for seconds at a time, neither party is talking. If we could remove these silent intervals, the file would be even smaller. Then, instead of sending a continuous stream of bytes (both silent and noisy), what if we sent just the packets of noisy bytes when you created them? That is the basis of a packet-switched phone network, the alternative to circuit switching.

While circuit switching keeps the connection open and constant, packet switching opens a brief connection -- just long enough to send a small chunk of data, called a packet, from one system to another. It works like this:

• The sending computer chops data into small packets, with an address on each one telling the network devices where to send them.
• Inside of each packet is a payload. The payload is a piece of the e-mail, a music file or whatever type of file is being transmitted inside the packet.
• The sending computer sends the packet to a nearby router and forgets about it. The nearby router send the packet to another router that is closer to the recipient computer. That router sends the packet along to another, even closer router, and so on.
• When the receiving computer finally gets the packets (which may have all taken completely different paths to get there), it uses instructions contained within the packets to reassemble the data into its original state.

Packet switching is very efficient. It lets the network route the packets along the least congested and cheapest lines. It also frees up the two computers communicating with each other so that they can accept information from other computers, as well.

Let's say that you and your friend both have service through a VoIP provider. You both have your analog phones hooked up to the service-provided ATAs. Let's take another look at that typical telephone call, but this time using VoIP over a packet-switched network:

1. You pick up the receiver, which sends a signal to the ATA.
2. The ATA receives the signal and sends a dial tone. This lets you know that you have a connection to the Internet.
3. You dial the phone number of the party you wish to talk to. The tones are converted by the ATA into digital data and temporarily stored.

   VoIP TermsThe central call processor is a piece of hardware running a specialized database/mapping program called a soft switch. See the "Soft Switches" section to learn more.

4. The phone number data is sent in the form of a request to your VoIP company's call processor. The call processor checks it to ensure that it is in a valid format.
5. The call processor determines to whom to map the phone number. In mapping, the phone number is translated to an IP address (more on this later). The soft switch connects the two devices on either end of the call. On the other end, a signal is sent to your friend's ATA, telling it to ask the connected phone to ring.
6. Once your friend picks up the phone, a session is established between your computer and your friend's computer. This means that each system knows to expect packets of data from the other system. In the middle, the normal Internet infrastructure handles the call as if it were e-mail or a Web page. Each system must use the same protocol to communicate. The systems implement two channels, one for each direction, as part of the session.
7. You talk for a period of time. During the conversation, your system and your friend's system transmit packets back and forth when there is data to be sent. The ATAs at each end translate these packets as they are received and convert them to the analog audio signal that you hear. Your ATA also keeps the circuit open between itself and your analog phone while it forwards packets to and from the IP host at the other end.
8. You finish talking and hang up the receiver.
9. When you hang up, the circuit is closed between your phone and the ATA.
10. The ATA sends a signal to the soft switch connecting the call, terminating the session. Probably one of the most compelling advantages of packet switching is that data networks already understand the technology. By migrating to this technology, telephone networks immediately gain the ability to communicate the way computers do.

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How it works

Voice over internet protocol (VoIP) is the latest technology that uses the internet to transport you call as opposed to the traditional public telephone switched network (PTSN). By using the reliability of the internet and leveraging its low costs, calls can be made anywhere in the world using VoIP technology . CDC allows you to capitalise on this and process calls worldwide without the cost of the ingress.

By taking advantage of H323, the international standard in VoIP, CDC can offer a variety of services at greatly reduced costs compared to traditional carriers. In addition to this, new revolutionary features such are possible such as our Callshop Solution and Telemarketing System.

Making a call from VoIP to a Regular Telephone

1. Any regular analogue telephone can be connected to one of the CDC ITG range of gateways. 2,4 or 8 telephone ports for up to 8 separate phone numbers. It is shipped pre-configured by CDC.
   
2. Connecting a CDC ITG to your network is simple. All you need is a broadband connection and an extra ethernet port on your hub or switch.
   
3. Once the CDC ITG is connected to the internet it automticaly finds the VoIP Gateway(s) and registers itself so that calls can be made and received. This makes your phone number extremely portable and will work anywhere in the world where there is an internet connection -- a feature not available with traditional services.
   
4. In this scenarios the CDC ITG is the originating gateway that converts your voice signals to VoIP packets which will travel over the internet.
   
5. The terminating gateway then converts the VoIP packets back to voice signals and connects to the PTSN (Public Switched Telephone Network) to make the call to any telephone in the world.

Making a call from a Regular Telephone to VoIP

1. The person calling you places a call using any regular telephone and dials a regular number.
   
2. The voice signals travel over the PTSN ( Public Switched Telephone Network ) to an Enterprise VoIP Gateway.
   
3. 1. The vocie signals are then converted to VoIP packets that travel over the internet to your CDC ITG which is connected to the internet regardless of where you are in the world. This makes your phone number extremely portable and will work anywhere in the world where there is an internet connection -- a unique feature with this product.
   
4. If you are in London, Spain or anywhere else in the world with a broadband internet connection and the person calling you is in the country that your soft switch is located calls can be made without incurring any international charges.