Voice over IP
Voice over IP
Habib Ullah
Habib Ullah
12-MS-CSc-12
12-MS-CSc-12
Contents

Abstract

What is VoIP

How VoIP works

VoIP Architecture

Components

Pros & Cons

Summary
Abstract

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 analogy
PSTN (Public Switched
Telephone Network) lines.

No dedicated path between
sender and receiver.

It acquires and releases
bandwidth, as it needed.

Cost is not based on
distance and time.
PBX
Yesterday’s Networks
Circuit Switched Networks (Voice)
CO
PBX
CO
CO
Packet Switched Networks (Data)
Router
Router
Router
Router
Router
• Separated networks
• Separated applications/services
PBX
IP Phone
Converged Network
PSTN
CO
Gateway
Router

LT
S
©Telcordia Technologies, Inc.
Slide 10
IP Network
Multimedia
PC
Multimedia
PC
Initially, PC to PC
voice calls over the
Internet
VoIP Architecture?
PSTN
(DC)
Gateway
PSTN
(NY)
Gateway
Public Switched
Telephone Network
Gateways allow PCs
to also reach phones
…or phones to reach
phones
Components

VoIP Protocols

VoIP Gateway


Codecs are used to convert an analog voice
signal to digitally encoded version. Codecs vary
in the sound quality, the bandwidth required, the
computational requirements, etc.
Do Companies Want VoIP?
76% Will!
76% Will!
Network World asked 500 readers to assess
whether they would consider using voice over IP:
Key Business Drivers for LAN-Based Telephony and VoIP
81%
81%
59%
59%
38%
38%
26%
26%
0 50 100
Save Money
Save Money
Better Utilization of Bandwidth
Better Utilization of Bandwidth
Support Multimedia
Support Multimedia
Improve Network Management
Improve Network Management
Security Risks
