VoIP Training, Module 2

Voice over IP Online Course

Lesson 2 - Why VoIP?

B. Benefits of VoIP

Benefits of VoIP

Reduced long-distance costs
More calls with less bandwidth
More and better enhanced services
Administration and maintenance savings

Voice over IP can be a complex and expensive technology to install. What benefits can organizations see that would be an incentive to make a change to their well established telephone system?

Reduced long distance costs

Reducing long distance costs is always attractive but only realistic if those calls are being made to other locations of the same organization. Furthermore, the organization must have fixed rate, leased lines to those locations. If a long distance call enters the public telephone system, savings on that call cannot be realized.

Traditionally, leased lines to other locations were installed if the organization needed to move computer data between sites. By converting voice to data, voice could join the other data and be transmitted to other locations. As long as the voice did not increase the need for more bandwidth, and hence the leased line charges, long distance charges could be avoided. This concept is known as toll bypass.

VoIP provides the toll bypass benefit and, in fact, may use the same leased lines. Its natural to ask the question, "What is the difference between the two systems?" The answer is the packet. In order for IP to work, information is broken up into discrete sections, called the "payload", and control information is added to it in the form of a "header". The resulting combination is called a "packet". An example of control information is the address of the destination. Why go to all this trouble? Because each packet is independent and when transmitted on a packet switching network will find its way to the destination. In other words, a fixed link does not have to be established between one computer and every other computer the first one needs to communicate with.

Data networks are just naturally packet based and by converting voice to packets, they can be managed along with the other data on the system.

If you already have toll bypass using leased lines, switching to VoIP on a managed IP backbone may not save a lot of money. However, better management and increased services may still make it a worthwhile exercise.

More Calls with Less Bandwidth

Traditional voice digitization techniques require 64 kbps (thousands of bits per second) to function properly. This rate is a function of the way voice is digitized using a technique known as Pulse Code Modulation (PCM). PCM provides pristine voice quality and is the hallmark against which other voice digitizing methods are measured. The 64 kbps rate is responsible for the way T1 lines operate. Each T1 line has 24 channels of 64 kbps each (each channel is referred to as DS0) and was originally devised to transmit 24 long distance calls simultaneously.

Today, state-of-the-art toll quality voice can be achieved at as low as 2 kbps, but is more typically provisioned at 8 kbps. Methods of generating digitized voice below 64 kbps PCM can use several techniques. One is data compression, but not all digitized voice below 64 kbps is produced by compressing 64 kbps PCM voice. And the 8 kbps digitized voice is typically only produced when someone is actually talking. Silence suppression is also a key component of many of these techniques. In other words, when there is a lull in the conversation, no packets are generated.

If each voice stream requires 8 kbps, than one DS0 service can carry 8 conversations instead of one, a clear saving.

More and better enhanced services

No one will replace a system with one that has less features. Therefore the VoIP system has to at least equal the traditional PBX when it comes to voice services. These include the familiar ones such as call forwarding, call waiting, third-party calling (charging the call to a telephone other than the caller or the recipient), collect calling (charge reversal), caller identification, and so on.

VoIP also makes it easy to interact with services that are also data based such as e-mail and unified messaging as well as call centre applications.

These last examples fall into the category of Computer Telephony Integration (CTI). VoIP will further enhance CTI. This is especially true when the Internet and the World Wide Web are mixed in.

One intriguing new service applies to home workers. You can reach a worker who is at home by their extension number. When that worker is back in the office, their extension is still the same.

Administration and maintenance savings

Administration and maintenance savings fall into several categories.

One cable system to maintain. Since the telephone system and the LAN use the same cable system, UTP cat5, only one system needs to be maintained.
Administration can be centralized, probably within the IT group. Head count can be decreased.
Moves, adds and changes are easier to make. If an employee moves to a different floor, just relocate her telephone. The DHCP based IP phone will instantly put the employee back on the telephone system. Her extension will stay the same.

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