VoIP for Dummies 2005

58 Part I: VoIP Basics

As mentioned, the main site in the South Hills had Internet service, but none of the other ten sites could access it. In the second month, we used some of the money they were saving to put in an Internet gateway in the South Hills. Now every location could access the Internet through the company’s VoIP network.

By the second month of implementing VoIP, their intralata toll service charges had dropped to $184 because all interoffice voice traffic was now carried on their private VoIP network instead of the regulated PSTN. Moreover, they could now understand the single bill that covered their entire VoIP network services; this alone brought sanity to their operation. In addition, all eleven locations could now access the Internet. They were already beginning to plan their Web site design and working out processes with their suppliers to use several e-commerce applications that were not possible before VoIP.

Some startup costs were not exactly inexpensive. However, their savings from VoIP more than covered these costs with money left over. Figure 3-4 is a breakdown of what it cost to bring VoIP to their enterprise.

Applying VoIP to your situation

The moral of this story? If your company has facilities distributed across more than one local calling area within the same LATA, look at your intralata toll charges. If all your sites switched to VoIP, you’d eliminate most, if not all, intralata charges you currently incur.

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In addition, you may be able to add services you never thought possible and pay for the services through your savings. In the case of my client, the VoIP network saved them more than $9000 per month even after all startup costs were paid. In addition, they expanded dedicated Internet access to all their locations, upgraded their telephone systems to support VoIP, and acquired needed equipment to make the changes. At the end of the first year under VoIP, their annualized savings were just under $112,000. In short, they got greater service and spent a lot less money. Figure 3-5 summarizes the costs and savings over the first year for this VoIP conversion project.

Do you already have a computer network connecting all your sites, or can you readily upgrade to connect all sites? If so, the cost of going to VoIP is greatly reduced because VoIP operates on the same network as your computer data.

CSI: Telephony

All types of networks operate within a much larger structure known in the telecommunications industry as a carrier services infrastructure (CSI). The carrier services infrastructure is an abstract concept for most people. As you begin to discover the various VoIP network types (such as DSL or a T1 line), it’s essential to know about each network type’s underlying CSI. Whatever network type you may choose to use for your VoIP, it is always a subnetwork of a larger CSI.

Figure 4-1 identifies the CSIs. We get into the details of each CSI later. For now, just focus on the fact that there are five CSIs through which all public and private communications travel.

Switched

The different CSIs are theoretically owned by the carrier companies that lease the various network transports and services. But in reality you can’t own something that exists largely in abstract terms. A good analogy is the National Football League. Is it owned by the NFL? We could say that it is. But to be more correct, we might say that it’s owned by all the teams that make up the NFL. And an individual NFL team exists by virtue of the NFL granting (selling and approving) a team franchise.

Truth be told, the NFL doesn’t own much of anything in the physical sense of the word. Football fields are owned by their respective teams. NFL players are said to be owned or at least under contract by their specific team.

At the same time, the NFL is not totally out of the picture. We hear lots about the NFL regarding regulatory measures and enforcement actions they may take against teams and players in the NFL. The NFL sets the rules for all teams to operate collectively. All the football stadiums together, with the players and the games they play, form the NFL.

of many buildings, a single location with one or more floors, or just a residential customer looking to reduce your monthly telephone bill and improve your Internet access. Ultimately, deciding what transport to use becomes the key decision point for any network, including VoIP.

To better understand transports, consider the T1 transport, easily the most popular dedicated transport in the corporate sector. It’s not unusual for companies to have many T1 lines throughout their private network. One reason that T1 lines are popular is because the bandwidth they provide can be optimized using dynamic channel allocation. This means a T1 line can be subdivided into twenty-four smaller bandwidth channels. These channels may be assigned to a bandwidth pool that supports computer data, VoIP, and video traffic. The terminating equipment for the T1 line can assign, at the moment needed, a specific channel or group of channels to bring up a VoIP telephone call or a videoconference call. When the need is over, the channels are returned to the bandwidth pool.

Dynamic bandwidth allocation is not available on all network transports. This is one of the reasons why it is important to know what type of transport or transports you’re planning to use. Your carrier may or may not make these points of distinction in a transport leasing deal. Dedicated (private) transports are not owned by the customer; they’re leased and there is a monthly access charge based on the distance from point A to point B. But the higher cost of dedicated transports is well worth it.

An important rule to follow when selecting network transports is to start with the question “What will we be using the network for?” This leads to a discussion of uses for network transports. These applications (uses) are called transport services.

Any transport can be used for one or more transport services. A POTS line, for example, is used for telephone services. Many customers use a POTS line at home for computer modem dialup services or to support broadband DSL services. As a result, a POTS line running DSL can support VoIP telephony in the home.

A T1 transport is often called private line service because it’s dedicated to the customer’s use. None of the carrier’s other customers or customers of other carriers can share the line. The customer may run all sorts of applications (transport services) on the T1 line. These applications may include computer data, VoIP telephony, and videoconferencing.

VoIP is considered first and foremost a transport service. VoIP runs on many of the same transports that support computer data and video. It uses packetswitching protocols to support telephony services, so it has the potential to eliminate or replace older transports and services that can’t integrate data, voice, and video on the same transport.

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The carriers of the future need to incorporate VoIP and related products and services into their business offerings. The most successful carriers are those that not only include VoIP but can lease VoIP services out of two or more of the five CSIs.

The Five Golden Rings of CSI

It’s useful to understand from which CSI a network transport service comes. The CSI to which a transport service belongs affects the way in which that transport service is implemented. Figure 4-2 shows the five types of CSI, along with popular transports and VoIP transport services.

As an example of how a CSI and transport can affect a transport service, consider the case of VoIP. An integral part of VoIP is the concept of transmitting voice packets over the transport. But each CSI, each transport, and the VoIP transport service provided therein support voice packets differently. This is because each CSI operates with different underlying protocols.

A transport line on the PSTN CSI, for example, is a limited bandwidth, circuitswitched medium that can support telephone services. A T1 transport is a much higher bandwidth line out of the DS CSI that can support many transport service applications that use packet-switching protocols. Although VoIP works under both the PSTN and DS CSIs, the faster T1 transport on the DS CSI affects the efficiency with which VoIP operates. If you’re thinking about using VoIP or have concerns about the operation of your existing VoIP, evaluate your network transports and transport services, paying particular attention to which CSIs are involved.