2. Talk Overview :
Introduction
VoIP- Packet Switching
Major Concerns of VoIP
CODEC
Quality of Service
Advantages of VoIP
Future Concerns of VoIP
Conclusion
Refrences
3. Introduction
Voice over Internet Protocol (VoIP) is a technology that
enables one to make and receive phone calls through the
Internet instead of using the traditional analog PSTN (Public
Switched Telephone Network) lines.
The voice-over-Internet protocol (VoIP) technology allows
voice information to pass over IP data networks.
VoIP converts the voice signal from your telephone into a
digital signal that travels over the Internet then converts it back
at the other end so you can speak to anyone with a regular phone
number.
4. Basic Flow Of VoIP Network
Signaling: Signaling in a VoIP network is accomplished
by the exchange of datagram messages between the
components. The format of these messages is covered by
the standard datalink layer protocols.
Database service : Database services are a way to locate
an endpoint and translate the addressing that two
networks use.
Call connect and disconnect (bearer control) : The
connection of a call is made by two endpoints opening
communication sessions between each other.
CODEC operations : Voice communication is
analogue, while data networking is digital. Analogue
waveforms are converted into digital information by using
a coder-decoder (CODEC).
5. Flavors of VoIP
ATA :
• Connects a standard phone to a computer or an
Internet connection for use with VoIP.
• The ATA is an analog-to-digital converter.
IP Phones :
• connect directly to a router and have all the hardware
and software necessary right onboard to handle the IP
call.
Computer-to-Computer :
• There are several companies offering free or very low-
cost software that you can use for this type of VoIP.
• All you need is the software, a microphone, speakers, a
sound card and an Internet connection.
7. VoIP converts the voice signal from your telephone into a
digital signal that travels over the Internet.
If you are calling a regular phone number, the signal is
then converted back at the other end.
Internet Voice can allow you to make a call directly from a
personal computer.
If you make a call using a phone with an adaptor, you’ll be
able to dial just as you always have.
8. Packet Switching
The users voice (or fax) is converted into a digital
signal, compressed, and broken down into a series of
packets.
The packets are then transported over private or public
IP networks and reassembled and decoded on the
receiving side.
At the receiving end, the re-assembled packets arrive as
a normal sounding voice call.
Packet switching is very efficient. It lets the network
route the packets along the least congested and cheapest
lines. It also frees up the two computers communicating
with each other so that they can accept information from
other computers, as well.
9. A Typical VoIP Network
VoIP data travels over the networks in packets.
In VoIP digitized voice is bundled into IP packets and
sent out into the network for delivery.
Routers, switches, and other network equipment direct
the packets to their destination IP address. This mode is
called packet switched telephony.
The transport of voice packets is affected by several
factors, such as the amount of bandwidth available in the
network connection, the delay that the packet experiences,
and any packet loss or corruption that occurs. The ability
of the network to deliver the voice packets quickly and
consistently is referred to as Quality of Service (QoS).
10. Major Concerns Of VoIP
Gateways: The gateways are the devices that
communicate between the telephone signals and the IP
endpoint.
Gatekeepers: gatekeeper knows how many users are
connected and where they are located. The collection of a
gatekeeper and its registered endpoints is called as a zone.
IP Telephones: These are devices, which replace the
existing telephones by providing enhanced services suited
to VOIP.
PC Software phones: This arrangement consists of a
microphone connected to a PC interfaced by a card and
running software, which permits voice and multimedia
transfer over the Internet. Microsoft NetMeeting, Skype
and Viber are an example.
11. VoIP CODECS
A codec which stands for coder-decoder, converts an
audio signal into compressed digital form for transmission
and then back into an uncompressed audio signal for
replay. It's the essence of VoIP.
Codecs sample the audio signal several thousand times
per second.
Summary of available codecs:
G.711 64 kbps
G.721 32 kbps
G.728 16 kbps
G.729 8 kbps
VoIP software processes and routes
the calls.
12. VoIP QoS (Quality Of Services) Issues
Quality of Service is essential for the success of VoIP.
The human ear is extremely sensitive to even minor
changes in an audio signal.
Loss of quality occurs when the voice packets are
transferred over the inherently unreliable packet-based
networks.
Some methods to enhance the QoS achieved in VoIP are:
Classification of Service: Using the TOS bits in the IP
header to set a priority for the voice packet.
Tagging the packets with labels and using the labels to
decide the route. Voice packets can be routed over less
congested networks.
13. Delay : Delay causes two problems: echo and talker
overlap. Echo is caused by the signal reflections of the
speaker's voice from the farend telephone quipment
back into the speaker's ear.
Jitter : The delay problem is compounded by the
need to remove jitter, a variable interpacket timing
caused by the network a packet traverses.
Lost-Packet Compensation : Lost packets can be
an even more severe problem, depending on the type
of packet network that is being used. Because IP
networks do not guarantee service, they will usually
exhibit a much higher incidence.
Echo Compensation : These reflections of the
speaker's voice are heard in the speaker's ear. Echo is
present even in a conventional circuit-switched
telephone network.
14. Advantages of Using VoIP
With VoIP mechanism you can talk all the time with every
person you want. (the needed is that other person is also
connected to Internet at the same time)
Integration of Voice and Data : The integration of voice
and data traffic will be demanded by multi application
software. The inevitable evolution will be web servers
capable of interacting with voice, data and images.
Simplification : An integrated infra structure that supports
all forms of communication allows more standardization and
lesser equipment management. The result is a fault tolerant
design.
15. Continued….
Network Efficiency : The integration of voice and
data effectively fills up the data communication
channels efficiently, thus providing band width
consolidation. The idea is to move away from the TDM
schema where in the user is given bandwidth when he
is not talking.
Cost reduction : The Public Switched Telephone
Networks' toll services can be bypassed using the
Internet backbone, which means slash in prices of the
long distance calls.
16. Future of VoIP Telephony
Several factors will influence future developments in VoIP
products and services. Currently, the most promising
areas for VoIP are corporate intranets and commercial
extranets. Their IP– based infrastructures enable
operators to control who can—and cannot—use the
network.
Another influential element in the ongoing Internet-
telephony evolution is the VoIP gateway. As these
gateways evolve from PC–based platforms to robust
embedded systems, each will be able to handle hundreds
of simultaneous calls.
17. Continued…
Commercial extranets, based on conservatively engineered IP
networks, will deliver VoIP and facsimile over Internet protocol
(FAXoIP) services to the general public.
Today’s Advanced Intelligent Network (AIN) provides many
useful features common to callers today. These features include
Caller ID, Voice Mail, Call Waiting, Pre-and-post paid calling
cards, 911, Call Blocking.
19. Interconnected VoIP Service
Interconnected VoIP service allows you to make and receive
calls to and from traditional phone numbers using an Internet
connection, possibly a high-speed (broadband) Internet
connection, such as Digital Subscriber Line (DSL), cable
modem, or wireless broadband.
It can be used in place of traditional phone service.
Typically, interconnected VoIP technology works by either
placing an adapter between a traditional phone and Internet
connection, or by using a special VoIP phone that connects
directly to your computer or Internet connection.
While you may choose to use interconnected VoIP service
from a single location, like a residence, some interconnected
VoIP services can be used wherever you travel, as long as a
broadband Internet connection is available.
20. Conclusion
VoIP technology offers broadband services and the
integration of voice and data at all levels. One key factor
that is driving the VoIP application development and
deployment is reduced voice service charges.
In addition to cost advantages, VoIP services have
compelling technical advantages over circuit switching.
Moreover, VoIP is suitable for computer telephony
integration and other next generation applications.
A VoIP network can centralize much of its intelligence
so the management of the network can also be
centralized.
21. Continued….
A service provider can centralize the network
operations and billing. Enterprises can also deploy an
IP telephony system.
VoIP will no longer be a service but a technology
that is utilized in an application that may run on a
computer, a PDA or other information and
communication appliance.
VoIP is growing fast. The very knowledge of the
applications of this technology is enough for users and
manufacturers to flock towards it. It is ideal for
computer based communications and at the same time
bringing down the cost of multimedia transfer.
