IP Telephony Unveiled

IP Telephony Unveiled

(8)

Figure 1-3 illustrates how an IP gateway (often referred to as an IP blade) that

is added to the existing PBX gives those PBX users the ability to place calls over

a company’s IP network from location to location in order to reduce long-distance

charges. Toll-bypass, as this is commonly referred to, is the most obvious benefit

of this type of VoIP deployment.

In Figure 1-3, the IP gateway could easily be a single card that is installed/

integrated into the PBX as are other cards on a PBX shelf. Furthermore, it could

be a card within a data router that currently resides on a company’s IP network.

Either approach (integrated as a card in the PBX or a router) provides

organizations with a cost-effective means for integrating gateways into their

environments. For many companies, reducing long-distance charges has been the

desired state, and upon accomplishing this task, they move on to other projects. In

their minds, their VoIP project is completed.

The Telephone as Client

Many organizations, however, see VoIP as far more than this. More than

simply using the network as transport (or plumbing), many organizations see value

in not only placing voice “traffic” onto the IP network, but also in placing the

actual voice “clients” (the telephones themselves) and new voice applications onto

the IP network. This approach, although technically still VoIP, is commonly

referred to as IP telephony; i.e., deploying a total telephony solution (including

telephones, components, applications, and by extension, users) within the IP

network.

In other words, IPT takes the premise of voice and data integration to its

natural, albeit long-awaited conclusion: new voice clients (telephones, wireless

devices, and desktop software) that, in their basic form, are designed to interface

and interact with an IP network, obeying the rules of the IP network, utilizing its

protocols, managed by its resources, and most importantly, accessing the myriad

of applications that (can) exist on the network.

NOTE Whereas VoIP places voice traffic on the IP network, IP telephony

places voice clients, applications, and traffic on the IP network,

thereby providing a different value proposition.

Chapter 1: Haven’t We Been Here Before?

(9)

As shown in Figure 1-4, IP telephony allows phones to be directly connected

to the IP network. A new type of phone, called an IP phone, is designed to

interface directly to the Ethernet switch on the IP network, much like any other IP

device, such as a PC, a laptop computer, or a network printer.

Figure 1-4 IP Phones Connect Directly to the IP Network

So, for the purpose of this book, VoIP is defined as technology that places

voice traffic onto the IP network, whereas IP telephony is technology that places

voice clients and voice applications as well as voice traffic onto the IP network.

Each technology has a different goal, or desired state. The value proposition

provided by IPT is very different than what was described previously for VoIP,

primarily because the desired state for IP telephony is different.

The question most often asked by companies who investigate IP telephony is

a simple one: Why should I put my telephones on the IP network? The simple

answer is because managing one network instead of two (or more) is easier and

more cost-effective, and that is where the majority of applications reside.

Unlike the traditional applications generally associated with voice, this new

breed of applications is different. New applications are being developed quickly,

with fewer resources, and at a lower cost. Instead of developing applications

against a specific vendors’ proprietary operating environment, IPT allows

organizations to write applications using industry-standard (and widely used) data

languages and protocols. In this new environment, just as data applications are

written using Java, XML, HTML, Visual Basic or other similar tools, so too are

new voice applications. Application development time is reduced from years and

months to days and weeks. At Selsius Systems, we saw this trend develop in front

of our eyes.

PBX

PBX

IP WAN

IP

Gateway

IP

Gateway