Voice over IP
Information Systems 311
November 19, 2002
How do computers communicate
1968 ARPA created a standard by which these computers could
communicate known as TCP/IP.
TCP/IP specifies the details of how computers communicate as well
as a set of conventions for interconnecting networks and routing
traffic.
TCP/IP is the standard by which computer communicate whether its
an internal client/server (little “internet”) or one connects through
other networks that spans geographic distance (big “Internet”)
Therefore TCP/IP is the base technology for the Global Internet that
connects over 170 million individuals in virtually all populated
countries around the world.
Some Differences
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TCP - transmission control protocol
Connection orientated circuit (established connection
between two hosts and exchanges streams of data)
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Considered a reliable protocol because it guarantees
delivery of data and the order of the packets that its
sending.
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Down-side – requires constant bandwidth to maintain the
connection
TCP/IP layers where split in the seventies to handle larger
volumes of information
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More
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IP – Internet Protocol
Connection-less orientated circuit
IP works on the packet level
Specifies the format of the packets and the addressing
scheme
Consider unreliable – individual packets send by by effort
routing and can arrive out of order.
Packets are switched doesn’t require constant bandwidth
Benefit IP packets can encapsulated with several types of
information like Voice
TCP/IP work within the Internet Model
The Internet’s 5-Layer Model (top – down hierarchy)
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Application: used by application program - the start of the five layer process.
Transport: establishing end-to-end connections, translates
domain names into numeric addresses, and segments
messages (also known as the TCP layer)
Network: responsible for end-to-end addressing and routing,
determines destination address if unknown (also known as IP
layer)
Data Link: deals with message delineation, error control &
network access
Physical: defines how information will be transmitted through
the network
continued...
VoIP – Definitions
What is it?
 How does it work?
 Standards involved
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VoIP – What is it?
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Voice over Internet Protocol
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Introduction of VoIP in 1995 by
Vocaltec Inc.
VoIP – How does it work?
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Converting the voice signal
– ADC (analog to digital)
– DAC (digital to analog)
Voice (source) - - ADC - - - Internet - - - DAC - - Voice (dest)
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Transmission of voice traffic in
packets
VoIP – Standards Involved
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H.323 V.2 – Most widely supported
– used for packet based multimedia communication
systems
Media Gateway Control Protocol
(MGCP)
 Session Initiation Protocol (SIP)
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VoIP – Applications
VoIP could be applied to almost any voice
communications requirement, ranging from a
simple inter-office intercom to complex multi-point
teleconferencing/shared screen environments.
For example…
continued...
VoIP – Applications
A network configuration of an organization with many branch
offices (e.g., a bank) that wants to reduce costs and combine
traffic to provide voice and data access to the main office.
continued...
VoIP – Applications
In this VoIP application, an organization wishes to send voice
traffic between two inter-office locations over the packet
network and replace the PBXs connections at these locations.
continued...
VoIP – Applications
A third application of VoIP software is inter-working with
cellular networks.
VoIP – Applications
Other applications:
• e-commerce – multi-service
applications (call button)
• conferencing systems that may
include shared screens,
whiteboarding, etc
Marketing application for Venetian
VoIP – Pro and Cons
Benefits of the VoIP technology can be
divided into the following four categories:
•
Cost Reduction
• Simplification - an integrated infrastructure
• Bandwidth Consolidation
•
Advanced Applications
VoIP – Pro and Cons
VoIP – Pro and Cons
Quality-of-service (QoS) issues
• Delay problems: echo, talker overlap
and jitter
• Too many standards
VoIP – Pro and Cons
VoIP – Security Issues
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Transmissions
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Unauthorized use
Solution for transmission issue
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Check Point Software
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Aravox
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Nortel Networks
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Aspect Communication
Security - Check Point Software
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Stateful Inspection of Web services traffic
from the network layer to the application
layer
 Centralized management with
SmartCenter
 Authentication, authorization and secure
sign-on with UserAuthority(TM)
 Prioritization of Web services traffic using
Check Point's Quality of Service (QoS)
solution, FloodGate-1
Security - Aravox
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Provides a limitless platform for voice
service providers.
 E.g. IP Centrex unified messaging, instant
conferencing, presence and instant
messaging
 Aravox was the first company creating a
carrier-class real-time IP services gateway
enabling backbone carriers, access
providers and enterprises to deploy
secure, real-time communications on
converged networks
Solutions for unauthorized use
Use a personal identification number
 Restrict employees dialing access
 Track phone calls
 Employee monitoring
 Gateways eliminate crank calls and
telemarketers
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Other Solution
VPN
 VPN hardware and software
installation
 Use this over WAN
 Offers high strength encryption keys
 Protect both data and the networks
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The Telephone Network
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Originally designed for analog communications
only.
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Today, standard analog telephone service is called
POTS (Plain Old Telephone Service).
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Modem communications use the telephone
network to send digital data.
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Modems use carrier waves to send information
Traditional Long Distance
Pick up phone
 Dial
 Long distance provider
 Pay connection fee and per minute
charge
 Billed monthly
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VoIP Long Distance
Pick up phone
 Dial number
 VoIP provider
 Internet
 Receiver’s VoIP provider
 This eliminate large phone bill
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VoIP - Demonstration
Yahoo Messenger
I will use the Voice Over IP feature of the messenger
to Chat
This works world wide for free (except ISP fee)
For this Demonstration will be to Minnesota approx. 1500 miles away.
VoIP - Expected growth and future
By 2007 VoIP will account for approx. 75% of the
worlds voice services.
Many companies are using VoIP on their managed
private networks to save money
Extremely likely the PBX’s will offer IP as and
added value service – like IP/PBX phone system
Has fantastic potential for e-commerce applications