2. Abstract
IP telephony today has already received much interest from users in most of the
countries. It is technology that is suitable for a wide variety of firms and organizations
and also for household users. One of the great opportunities with VoIP is that
companies can enjoy an immediate cost benefit with their toll charges. VoIP can save
money in other ways, as well. We won’t need to pay any additional per-line feature
charges because VoIP runs on traditional computer network. Regulatory fees,
surcharges, and taxes are applied on a per-line basis. As we reduce the number of lines,
the line cost and recurring charges go with them.
What is Intranet
Intranet is the generic term for a collection of private computer networks within an
organization. An intranet uses network technologies as a tool to facilitate communication
between people or workgroups to improve the data sharing capability and overall
knowledge base of an organization's employees. Intranets utilize standard network
hardware and software technologies like Ethernet, WiFi, TCP/IP, Web browsers and Web
servers. An organization's intranet typically includes Internet access but is firewalled so
that its computers cannot be reached directly from the outside.
The business value of intranet solutions is generally accepted in larger corporations, but
their worth has proven very difficult to quantify in terms of time saved or return on
investment.
Some of the main purposes that organization use intranets for are:
• Consolidating corporate data into a central location
• Improving internal communication
• The creation of new opportunities for collaboration
• Increasing organizational effectiveness and productivity
• Saving costs
What is VOIP
VoIP "Voice-over-IP" As defined by the Tec Encyclopedia: The two-way transmission of
audio over a packet-switched IP network (TCP/IP network). When used in a private
intranet or WAN, it is generally known as 'voice over IP,' or 'VoIP.' When the transport is
the public Internet or the Internet backbone from a major carrier, it is generally called
'IP telephony' or 'Internet telephony.'
The data network involved might be the Internet itself, or a corporate intranet, or
managed networks used by local or long distance carriers and ISPs. Who runs the
network doesn't matter -- what does is the fact that we're taking voice (i.e., analog
information) and encoding it digitally, converting it into packets, and then using a data

3. network to move those packets along the most efficient path to their destination, where
they get reassembled and delivered in the format they started in voice.
The term IP Telephony used largely interchangeably with Voice over IP and VoIP to
describe the transmission of voice -- in this case referring more specifically to voice in
the form of live calls, rather than messages -- over data networks.
Who could be the IP Telephony User
IP telephony use is suitable particularly for those users who
• do not want to keep two separate network infrastructures - one for data transfer
and the other for voice transfer
• do not want to call a telephone switchboard servicing technician during every
change in the numbering plan or when adding users
• do not want to procure a branch switchboard for each of their locations
• want to unify voice and data services
• want to utilize the new services that IP telephony offers
• want to increase their productivity
Existing Voice and Data Network in the large organization
Most of the organizations in our country use the separate networks for the DATA and
VOICE services. For the data network we are using intranet through the data service
network provider. The connection between the branches of the organization may be
optical fiber, wireless or DDN. On the other hand the voice network service is still in the
Circuit-Switched (POST/PSTN) network or mobile phone. Sometimes mobile phone
network is not available so the main and reliable telephony system for the organization
is PSTN which is government organization and we have to pay for every dedicated
phone line to the government.
Figure: Separated DATA and VOICE Network.

4. Deploying Voice over IP in some form is usually seen as a key element in a drive
towards convergence because voice is typically a large component in any converged
voice/data/video infrastructure. More important, the case for VoIP in the enterprise has
shifted from pure cost savings to a dynamic combination of strategic financial and
business benefits that underpin an agile, flexible, competitive business model. The key
change is that voice and data can now be carried over a single converged IP network.
Calls within that network travel toll-free and because IP reaches beyond the
organizational boundaries, the benefits and the savings can be delivered across an
extended enterprise to remote workers, branch offices, suppliers and partners. IP-based
voice quality has now matured and closed the gap on its circuit-switched predecessor,
thanks to recent networking developments.
Figure: Integrated DATA and VOICE Network.
Voice and Data Network Characteristics
The two networks have different characteristics as shown in Table 1 and core beliefs. It
is the beliefs that affect costs and availability. The telephony industry is old, well-
established, and has a track record of being market-blind. It provides Plain Old
Telephone Service (POTS) which carry data at a maximum of 56 Kbps today. The core
belief of telephony service guaranteed bandwidth on maximum-demand. Service can
only be guaranteed using circuit switches and pre-allocating time-slots on high capacity
channels. This approach does not benefit from statistical sharing of resources.
The decades-old data-communications industry supports LANs, WANs, and the Intranet
using IP (Internet Protocol) packet switching. The group of private Intranets for
corporations and other large organizations is built from a data-communications
equipment industry and telephony lines using Internet-compatible technology, tools, and
training. While the datacom world has the technological capability to make our voice and
data merged in one network. The core belief of the data-comm industry is packet

5. switching. By having adequate bandwidth and evolving the IP protocol, it believes it can
provide a single network for data, voice (e.g. the Internet Phone), video telephony, and
even broadcast television
POTS Datacom
Transmission and "core Circuit switched. Must install, Packet switched; Channel
belief" capacity for the worst case. capacity can be shared.
Twisted pair analog to the
Wide range of media. Like
home; High-speed time
Media division multiplexed digitally
Wireless, Optical Fiber,
UTP, STP etc.
sampled trunk lines.
Bandwidth 56 Kbps (max ISDN 128) Up to Gbps.
Short for RPC, voice and 2-
End-to-end delay Short
way video.
Data comm can tolerate
Sensitivity to delay delay. RPC, Voice and 2-
Variation must be very small
variations way video require low
delay.
Wide range, including
Nature of connection 3-5 min. calls
permanent connections
Table 1. Network characteristics for POTS and Data-communications
Why use VoIP
It could be two main reasons:
1) Properly chosen and implemented, IP solutions for key business approaches
(interoffice voice networking, remote agent/home worker, IP PBX/LAN telephony, etc.)
are cheaper to operate, maintain, and upgrade than comparable solutions using
switched digital or analog phone service.
2) IP solutions are also more powerful, flexible, feature-rich, and interesting than
conventional stuff.
VoIP has matured since its inception, and today saves companies huge amounts of
money. It provides a great quality of service over private, dedicated networks.
Moreover, VoIP enables a number of slick calling options. VoIP features enhance the
collaboration of employees across the enterprise and ultimately increase productivity
while reducing the operating expenses of the company.

6. Reducing or eliminating phone lines
If we can eliminate one or more of the lines that we lease from the carrier, the call
feature charges, the regulatory fees, and the taxes are also eliminated. Reducing the
total number of lines really makes a cost difference. In the POTS/PSTN way of doing
telephony, we get additional lines as we need to increase our capacity. In the VoIP way,
we can upgrade our bandwidth on our dedicated line to increase capacity.
There are several disadvantages for companies that use POTS/PSTN rather than VoIP
telephony. POTS-related lines are leased from a carrier. Just leasing a single line incurs
added expenses. For example:
• Each line usually has a nominal startup charge.
• Each line has a monthly recurring access charge.
• For each POTS line, the company must pay monthly recurring usage charges.
If our company has separate telephony and computer networks and the company has
significant aggregate toll volume, we can reduce or eliminate most of our charges by
converting to VoIP and running our telephony over our computer network.
Take off organization’s add-on charges
Traditional phone service normally includes costs that apply to every single line we
lease. Just like any other service, traditional telephony lines and services are taxed.
Depending on where we are located, we could have one or more taxes in addition to all
the other monthly charges. Taxes are based on the total cost of our line access and
other services
Taxes obviously affect our bottom line. VoIP, however, does not come with any taxes or
surcharges. VoIP is totally unregulated and operates over our existing computer
network. Therefore, taxes do not apply to our monthly bill.
With VoIP, we pay regulatory fees for our dedicated network transports, but we already
pay these in support of our computer data network. VoIP runs over our packetized
computer network, so we have no more taxes, add-on costs, or other regulatory costs
for VoIP telephony.
Free call features
Calling features include items such as voice mail, call forwarding, call transfer, return
call, and three-way calling. Traditional telephony requires we to pay a monthly charge
for call features. These add-on charges may not apply equally to all the lines we lease
because the features are optional. Some call features are so popular, many people think
they are a part of the telephone service and are expected to come with the access line.
Voice mail, for instance, is considered an essential with any telephone, However, we do
not have to add any call features to any line; they are truly options like a moon roof or

7. climate control in an automobile. VoIP comes with the usual call features that we have
to either bundle with our traditional lines or pay per line as we use these features. But
with VoIP, we don’t need to worry about the cost of call features; they are all included
at no extra cost.
Solution example
In the figure below presents a network topology that links a remote office to the
corporate headquarters via a wide area network (WAN), using ProCurve of HP (it can be
with CISCO, AVAYA, Nortel etc.) networking equipment in conjunction with a public
telephone network. The offices are connected via a packet-switched transmission
network (PSTN) and analog trunks to ensure against loss of service in the event that the
WAN is unavailable. The local PSTN also ensures that local phone service does not need
to traverse the WAN link and provides service to analog devices such as fax, modem,
and emergency 911 services.
In addition, this topology incorporates a legacy third-party PBX at the corporate
headquarters, to allow the enterprise a smooth migration to take advantage of IP
telephony without forcing an expensive forklift replacement.
Figure: ProCurve IP Telephony Solution Overviews

8. Ten Reasons Why Our Company Should Switch to IP Telephony
• Changing direction of the telephony industry
• Feature-rich, cost effective alternatives
• Existing investment protection
• Seamless maintenance and management
• Flexibility and portability
• Enhanced network management
• Better utilization of personnel
• Productivity applications
• Better bandwidth utilization
• Reduced costs
Conclusion:
By using IP telephony corporate organizations that have to spend much money for
telephony system can reduce this cost in vast. We have to only need one time
installation cost. But in the long term service it will be beneficial for the organization. By
merging Voice network with the Data network it will reduces the infrastructure cost and
managerial hassle. However, instead of being a Circuit Switched mechanism for
telephony, IP telephony is likely to develop as a component within an integrated system
of video, data and voice applications though the Intranet for the corporate. The
potential offered by IP networks for computer-telephony integration and the continuing
technological development in this area suggest that this will not be a transient
phenomenon. However, most uncertainties reside on the demand side and the diffusion
of IP telephony is still at an early stage. Instead of using public phone lines, IP
Telephony creates an alternative to paying long distance phone bills. Using this new
technology has many ideal advantages. It is cost effective, it allows easier
communication, is great for international use, and it can be very useful for large
corporations. However, there are also some negative factors of VoIP, such as voice
clarity and transmission delays. In time VoIP will become a new way to communicate
and will have a large effect on University, business, and personal communications.
REFERENCES
[1] http://www.about.com
[2] http://www.directonpc.com/atWork/casestudies.aspx
[3] http://www.procurve.com.
[4] http://www.wikipedia.com
[5] http://www.thus.net