The Future of Voice over Internet Protocol

uptightexampleΔίκτυα και Επικοινωνίες

24 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

75 εμφανίσεις

The Future of Voice
over Internet Protocol

Presenter: Scott Martin

April 12, 2007

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 21
st

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

References


Wikipedia. “Network Voice Protocol”. March 2007 (
http://en.wikipedia.org/wiki/Network_Voice_Protocol
)


Valdes, Robert. HowStufWorks. “How VoIP Works”. May 2001 (
http://electronics.howstuffworks.com/ip
-
telephony.htm
)


Protocols.com. “Voice Over IP Protocols”. March 2007 (
http://www.protocols.com/pbook/VoIP.htm
)


Bell, Michael. “Ways to Use VoIP”. 2007 (
http://ezinearticles.com/?Ways
-
to
-
Use
-
VoIP
-
Technology&id=125070
)


VoIP.com. 2007 (
http://www.voip.com/
)


AT&T.com. “AT&T International Rate Finder”. 2006
(
http://www.consumer.att.com/global/english/international.html
)


BellSouth.com. “International Calling Plan Rates”.
(
http://www.bellsouth.com/consumer/bsld/icpRates.html
)


Qwest. “Qwest OneFlex International Rates”. 2007
(
https://cvoip.qwest.com/oneflex/portal/residential/products/voip/ratesl
)


Verizon. “Country Code and International Rate Finder”. 2007
(
http://www22.verizon.com/ForYourHome/LD/WorldCaller.asp
)[10] FCC Consumer & Governmental
Affairs Bureau. “Voice Over Internet Protocol”. June 2006 (
http://www.fcc.gov/voip/
)


Wikipedia. “Voice Over IP”. March 2007 (
http://en.wikipedia.org/wiki/Voip
)


New Paradigm Resources Group. ISP
-
Planet.com. “Executive Summary, VoIP Report 3rd Edition”.
December 2006 (
http://www.isp
-
planet.com/research/2006/nprg_voip_summary.html
)