Understanding VoIP Basics

At its most basic level, VoIP is a technology that allows you to place a voice phone call over an Internet connection. It uses an Internet connection to pass voice data, using the Internet Protocol (IP) rather than using POTS (plain old telephone service).

VoIP’s applications are endless. Remote employees can work just as if they were hooked into your telephone system in-house, and because you’re using your Internet Service Provider (ISP) to make VoIP calls, you’re not getting charged by your long-distance carrier. Even though high-end VoIP setups cost a bundle to install, the technology ultimately keeps corporate telephone costs low, as long as your network is configured just right.

VoIP technology was initially used by modern-day versions of ham radio operators and computer geeks, who wanted to make free phone calls with poor quality over dialup Internet connections (remember dialup?). The processes and sophistication of VoIP has grown exponentially over the years, to the point where most long-distance carriers now use VoIP technology to transfer calls within their own networks, and large businesses are adopting this newer, higher-quality VoIP for their day-to-day operations.

The VoIP protocol not only converts your words into digital code, but also puts that code into packets for transmission across an Internet connection (this process is referred to as packetization). Your call eventually connects to another VoIP phone, or a piece of hardware called a gateway. At that point, the call is translated from VoIP to TDM (time division multiplexing protocol), a standard non-VoIP protocol that you can read more about in Chapter 8. From there, it’s sent on to the destination phone. Gateways bridge the VoIP and Non-VoIP worlds together by translating the protocols, allowing your call to reach your grandma’s rotary-dial phone — which is definitely not using VoIP.

Figure 15-1 shows how a call originates from your phone as VoIP and is transmitted along your Internet connection until it is converted to TDM with a VoIP gateway. Your call emerges from the gateway into the Public Switched Telephone Network, or PSTN, and is routed to the phone you dialed. Read the figure from right to left, rather than left to right, to see how calls originating from non-VoIP phones are received with VoIP.

Figure 15-1: Calls are transmitted using both the VoIP protocols and the TDM protocol.