The Future of Voice

over Internet Protocol

Introduction

• What is Voice Over Internet Protocol (VoIP)?

• The two-way transmission of audio over a

packet-switched 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 'Internet telephony’.

Introduction

• Voice Over Internet Protocol (VoIP)

– History

– Implementation

– Service Types

– Benefits

– Drawbacks

– Current and Projected Use

History of VoIP

• Network Voice Protocol

– Created in 1973 by Danny Cohen at USC

– Project Goals

• Wanted to create digital high-quality, low-bandwidth,

secure voice handling capability

– Control Protocol

– Data Transport Protocol

Circuit Switching

• Current Phone Systems

• Dedicated line with a constant connection

• Originally very expensive

• Each call transmits at 64 kilobits per second

– 64 kbps x 2 directions = 128 kbps

– 128 kbps = 16 kilobytes per second

– During a 10 minute call, about 10 MB

– Highly inefficient

Circuit Switching

• Example: Circuit Switching

Packet Switching

• VoIP Phone Systems

• Connection only long enough to send a

packet of information

• Thousands of possible paths for packet to go

• Network uses cheapest and least congested

paths

• Quality of Service (QoS)

• A 10 minute call transfers only about 2 MB

Packet Switching

• Example: Packet Switching

Quality of Service (QoS)

• Defined in the International

Telecommunication Union standard X.902

• A set of quality requirements on the

collective behavior of one or more objects.

• Control mechanisms to provide different

priorities to different users or data flows

• Important for real-time streaming applications

VoIP Implementation

• Sender picks up the phone

• Analog telephone adapter (ATA)

– Data converted by a codec

• Soft Switch

• Receiver picks up ringing phone

• Data transfer during calls is handled by

current internet infrastructure

Analog Telephone Adapter (ATA)

• Converts audio between analog and digital

signals

• Need one on each end of the call

• Sends signal to handle connect and

disconnect

Codecs

• Coder-decoder or codecs

• Conversion from analog audio signal to

digital signal

• Most common codec is the G.729A

– sampling rate of 8,000 times per second

• Conjugate-structure Algebraic-code-excited

Linear Prediction algorithm (CS-ACELP)

• Responsible for the large gap in performance

Soft Switches

• Database mapping program

• Endpoint-to-Endpoint

– Location

– Phone Number

– IP address

• Allows phones, computers, and WiFi phones

to work together

Industry Protocol Standards

• H.323 Protocol Suite

• Main flaw – not designed for VoIP

Industry Protocol Standards

• Session Initiation Protocol (SIP)

– Smaller, more efficient

– Designed specifically for VoIP

• Handles

– User location

– User capabilities

– User availability

– Call setup

– Call handling

VoIP Service Types

• Home Phones

– Requires an ATA

– Usually provided for free

• IP Phones

– ATA technology built in

– Ethernet Phones

– WiFi Phones

• Computer-to-Computer calls

Computer-to-Computer VoIP

• Simplest and cheapest way to use VoIP

• Requires

– Microphone

– Speaker

– Sound card

– Broadband internet

• Costs: Software and ISP service

• Calls: Free

• Example: Skype Download Service

Benefits

• Uses technology already in common use

• Cost

• Bundled Services

– Caller ID

– Voice Mail

– Call Waiting

– Call Forwarding

– Many Others

• Long Distance and International Rates

Benefits

Cost of Calls Made from US to Foreign Countries

Drawbacks

• 911 Emergency Calls

• Dependence on Wall Power

• Latency issues, jitter, and packet loss

• Viruses, worms, and hackers

• Integration with land-line dependant hardware

– DVRs, digital television service, and home security systems

Drawbacks

• Security

• Problems sending faxes

• Dependence on Internet Service Providers

• Requirement of broadband connectivity

• WiFi hotspot dependence

Current and Projected Use

• Roughly 6 million in US in 2006

• Expected to climb to 24 million by the end of 2008

• Increase in service providers

– Traditional phone companies • At&T, Sprint, Nextel, Time Warner

– VoIP companies • Skype, Vonage, VoIP Inc.

Conclusion

• VoIP will be a dominate force in the 21st century

• Probably at least another 10 years before possibly replacing current phone systems

• If the current flaws are fixed sooner rather than later, it could be much sooner than a decade