The ad campaign for a particular toothpaste brand claims that all the
beautiful girls in this world will get attracted to you and will say "Talk
to me!" if you use this toothpaste. Now, there is another technology coming
your way that will soon make everyone say "Talk to me!". That is Voice
over Internet Protocol (VoIP).
VoIP, as the name suggests, carries voice signals over the
Internet Protocol, which was initially designed to carry only digital data. It
can be seen as the ability to make telephone calls over IP-based data networks
with a suitable quality of service (QoS) and a much superior cost/benefit.
Equipment manufacturers are looking at VoIP as a new opportunity to innovate and
compete.
Telecom equipment manufacturers will try to build VoIP-enabled
equipment. Networking equipment manufacturers will try to build new equipment,
which can convert existing data networks into integrated voice and data
networks. The race can be won by quickly developing new VoIP-enabled equipment
that will do the job with minimum of rewiring. Successfully delivering voice
over data networks presents a tremendous opportunity.
However, implementing the products is not as straightforward
a task as it may first appear. The entire solution involves setting up the
infrastructure, software, and systems that will be necessary to realize VoIP on
a large scale. Product development challenges such as ensuring interoperability,
scalability, and cost/effectiveness are very important.
Critical to success is the ability to deploy value-added and
high-margin services. For example, you could deploy a unified messaging system
that would voice synthesize e-mails over a phone to the subscriber.
In the future, there will be telephony-aware applications
that are integrated into other business applications. One example of a
telephony-aware application is "click to call". The tools and the
communication devices we use will change when IP telephony is fully deployed.
Though VoIP is still new to India, packet-based telephony is
becoming more advanced all over the world. Voice protocols have further
developed to offer a richer set of features, scalability and standardization
than what was available a few years ago.
By driving voice and data traffic through the same pipes,
annual telephone bills can be dramatically lowered, by as much as 90 percent.
Payback time, depending on call volumes and network configurations, can be as
short as six months. From then on, savings can continue long into the future.
VoIP applications
There are basically three types of Voice over IP calls–PC
to PC, PC to Phone, Phone to Phone. Take for example, a company that already has
an IP network in place at locations in Bombay and Los Angeles. By placing a
voice gateway between the network routers and EPBXs at each site, voice traffic
can piggyback the WAN link between these cities.
As a result, expensive international calls can now be made
almost for free. Alternatively, if no WAN link exists, router-based Internet
connectivity can be used to make the voice calls over the Internet.
TCP/IP (transmission control protocol/Internet protocol) is
the basic communication protocol of the Internet. It can also be used as a
communications protocol in private networks like intranets and extranets. When
you set up a direct access to the Internet, communications take place over
TCP/IP. TCP/IP is a two-layered program.
The higher layer, TCP, manages the assembling of a message or
file into smaller packets that are transmitted over the Internet and received by
a TCP layer that reassembles the packets into the original message. The lower
layer, IP, handles the address part of each packet so that it gets to the right
destination.
Each router/gateway on the network checks this address to see
where to forward the message. Even though some packets from the same message are
routed differently than others, they will be reassembled at the destination. The
same process can carry packetized voice.
Voice quality
Voice quality is the first thing to get affected in VoIP.
However a delay between two end-points in one direction of less than 150
millisecond is considered an excellent quality level for voice. Delay can create
two potential problems.
The first is that long delays in conversation cause the talk
from two parties to overlap. The receiver may start talking, believing that the
sender has stopped talking, when in fact he has not.
The second problem is echo, or the reflection of the original
signal back to the sender. Echo is common in all voice transmission, but is
mostly unnoticed under low delay conditions. It becomes more noticeable when the
delay becomes too large. Echo chancellors are necessary to remove echo from such
conversations.
The most important standard specification for VoIP is the
H.323 specification, approved in 1996 by the International Telecommunications
Union (ITU). H.323 has been the de facto standard for interoperability between
different products for real-time communication over IP. The real-time
communication can be voice, video and other multimedia services.
VoIP components
Terminal is a PC or a standalone device running an H.323
protocol and the multimedia applications. A terminal supports audio
communications and can optionally support video or data communications.
The primary goal of H.323 is to interwork with other
multimedia terminals. Because the basic service provided by an H.323 terminal is
audio communications, a H.323 terminal plays a key role in IP-telephony
services.
VoIP gateway is a product that delivers data and voice over
an IP network. Gateway takes traditional telephony traffic, compresses it, and
then places the compressed information into an IP packet and "routes"
this into the IP network. Gateways adapt traditional telephony to the Internet.
Data packets are not sensitive to delays but voice packets are.
The routers must recognize the voice packets and handle them
on priority, so that they arrive at the receiver at a consistent rate. Further,
the sender and receiver must have VoIP equipment that are standardized and
compatible with each other.
A gateway connects two dissimilar networks. An H.323 gateway
provides connectivity between an H.323 network and a non-H.323 network. This
connectivity of dissimilar networks is achieved by translating protocols for
call-setup and release, converting media formats between different networks, and
transferring information between different networks connected by the gateway. A
gateway is not required however for communication between two terminals on an
H.323 network.
The gatekeeper can be considered the brain of H.323 network.
It is the focal point for all calls within the H.323 network. Although they are
not mandatory, they provide important services like address translation,
admission control, bandwidth management, zone-management and call-routing
services.
Multipoint control units (MCU) provides support for
conferences between three or more H.323 terminals. All terminals participating
in the conference establish a connection with the MCU. The MCU manages
conference resources, negotiates between terminals for the purpose of
determining the audio or video coder/decoder to use, and may handle the media.
The impact of VoIP
The impact of VoIP can be felt most in area of teleworking.
As the WTC attacks of September 11 in the US have highlighted, teleworking can
be an effective answer to avoid concentrated presence of highly specialized
manpower in a few high-rise buildings.
People are the biggest and most important asset a business
has, and teleworking can maximize the return on this investment. An IP-based
teleworking infrastructure with VoIP capabilities can let a team of individuals
work together effectively irrespective of their geographical location.