VoIP
— which stands for voice over Internet protocol and often pronounced “voyp” — is a new technology that will improve the way we communicate. VoIP basically means voice transmitted over a digital network. The Internet, however, isn’t strictly necessary for VoIP. What is necessary for VoIP technology is the use of the same protocols that the Internet uses. (A protocol is a set of rules used to allow orderly communication.) Thus, voice over Internet protocol means voice that travels by way of the same protocols used on the Internet.
VoIP is often referred to as IP telephony (IPT) because it uses Internet protocols to make possible enhanced voice communications. The Internet protocols are the basis of IP networking, which supports corporate, private, public, cable, and even wireless networks. VoIP unites an organization’s many locations — including mobile workers — into a single converged communications network and provides an unparalleled range of telephony support services and features.
In the beginning, there was POTS
Before digital networking took off, everyone had to use the one and only POTS (or plain old telephone service — honestly!). POTS runs over a network called the PSTN, or public switched telephone network. These POTS telephone systems use the tried-and-true method of telephone service known as circuit-switched.
For customers, the costs related to the regulated circuit-switched PSTN remain much higher than they need to be. Consumers and companies that rely daily on POTS know what the POTS way of telephony means to the bottom line. The good news is that VoIP is an alternative that can greatly reduce or eliminate POTS-related costs. VoIP also enhances productivity, leaving a bigger budget for things other than paying telephone bills.
From POTS to packets
VoIP technology enables traditional telephony services to operate over computer networks using packet-switched protocols. Packet-switched VoIP puts voice signals into packets, similar to an electronic envelope. Along with the voice signals, the VoIP packet includes both the caller’s and the receiver’s network addresses. VoIP packets can traverse any VoIP-compatible network. Because VoIP uses packets, much more information can be carried over the network to support and enhance your communication needs when compared to traditional telephony methods.
In a circuit-switched network such as POTS, routing is less dynamic than with a packet-switched network. In the POTS world, if a line is down, the call can’t go through. In a packet-switched network, multiple routes can be established, and packets can travel any of the available routes. If one of the lines supporting the network is down, the packet can switch to another working route to keep the call up.
With VoIP, voice signals can travel the same packet-switched network infrastructure that companies already use for their computer data.
Eye for IP telephony
VoIP also makes possible other services that older telephony systems can’t provide. VoIP telephony services are interoperable, meaning that they work well over all kinds of networks. They are also highly portable, which means they will work with any IP-enabled device such as an IP telephone, a computer, or even a personal digital assistant (PDA).
IP telephony works by taking traditional voice signals and converting them to a form that can be transmitted easily over a local area network. Thus, the heart of IP telephony is the same as traditional data networking with computers. IP-enabled phones handle the voice-to-data conversion well, but don’t be misled — implementing VoIP doesn’t mean everyone has to use IP-enabled phones. The best VoIP providers implement IP telephony in a manner that protects your investment in existing telephone equipment, even if you have analog telephone stations.
All IP phones have one important thing in common: a built-in network interface card (NIC), just like a computer uses. The NIC is critical for any network device because it provides the device with a standardized physical, or MAC, address and a way to communicate over the network. (MAC stands for media access control.)
To support IP telephony, a server is typically dedicated to run the software used to manage calls. Servers are just like PCs, except they have more memory, speed, and capacity. The server stores the database that contains all the MAC addresses corresponding to all the IP telephone extensions assigned to users. Depending on the size of the LAN and the number of users, you may use more than one server.
Depending on the size of the LAN, one or more switches are installed. These switches are boxes that have a series of ports into which all LAN-addressable devices (such as computers, printers, and gateways) ultimately connect. Usually, the switches are set up in the communications closets around the LAN, and they operate 24/7. All the switches are interconnected, often with fiber-optic cable.
In a nutshell, all network devices, including your IP telephone, must physically connect to the LAN through a port on a switch.