Voice Over Internet Voice Over Internet ProtocolProtocol

By Eric RiceBy Eric Rice

HistoryHistory First telephone was First telephone was

patented in 1870 patented in 1870 Rotary dialing first Rotary dialing first

done in 1891done in 1891 1905-Party Line1905-Party Line 1910-5.1 million 1910-5.1 million

customerscustomers 1941-Attacks on Pearl 1941-Attacks on Pearl

Harbor cause a 100-Harbor cause a 100-400 percent spike in 400 percent spike in long distance nation long distance nation widewide

History cont.History cont.

1949-the average calls placed in a day 1949-the average calls placed in a day reach 180 million.reach 180 million.

1975-there are 140 million telephone lines 1975-there are 140 million telephone lines in the US and AT&T controls 85% of themin the US and AT&T controls 85% of them

1993-AT&T offers Caller ID1993-AT&T offers Caller ID 1995-Vocal Tec release first VOIP software1995-Vocal Tec release first VOIP software 1996-First cable modem service offered by 1996-First cable modem service offered by

Roger CommunicationsRoger Communications 2001-Vonage founded2001-Vonage founded March 2002-Vonage initiates serviceMarch 2002-Vonage initiates service

The IssuesThe Issues

ReliabilityReliability 911 service 911 service

availabilityavailability Voice QualityVoice Quality

• DelayDelay• JitterJitter

FeaturesFeatures Signaling ProtocolSignaling Protocol

ReliabilityReliability

The current standardThe current standard• Five-nines (5 min of downtime a year)Five-nines (5 min of downtime a year)

““Networks go down all the time”Networks go down all the time” High Internet TrafficHigh Internet Traffic

911 Availability911 Availability

Currently address information is linked to Currently address information is linked to a numbera number

Due to VoIP portability, locations are not Due to VoIP portability, locations are not defineddefined

In order to receive 911 service it must first In order to receive 911 service it must first be set upbe set up

Mobile phones have this same problemMobile phones have this same problem Alternate solutions include developing new Alternate solutions include developing new

port mapping technologiesport mapping technologies Using GPS to locate callersUsing GPS to locate callers

Voice QualityVoice Quality

GoalsGoals• Make it comparable to wire lineMake it comparable to wire line• Minimize bandwidthMinimize bandwidth

Wire line Voice codec is G.711 Wire line Voice codec is G.711 • 64kbps64kbps• MOS 4.3 (mean opinion score)MOS 4.3 (mean opinion score)

VoIP Voice codec G.729VoIP Voice codec G.729• 8kbps8kbps• MOS 4.0MOS 4.0

What?

Other CodecsOther Codecs

These codecs use These codecs use a number of a number of different different compression compression algorithms to algorithms to minimize required minimize required bandwidthbandwidth

DelayDelay

Delay is measured Delay is measured using Round Trip using Round Trip TimeTime

Keep delay less Keep delay less then 300msthen 300ms• If greater then If greater then

300ms may seem 300ms may seem like making an like making an international call: international call: take this situation take this situation

Person APerson A Person BPerson B

A SpeaksA Speaks

B interrupts and B interrupts and starts talkingstarts talking

A hears B’s A hears B’s interruption and interruption and stops talkingstops talking

B stops talking B stops talking because they because they think A ignored think A ignored the interruptionthe interruption

B hears A and B hears A and stops talkingstops talking

Uncomfortable Uncomfortable silence silence

Uncomfortable Uncomfortable silence silence

A starts talkingA starts talking B starts talkingB starts talking

A hears B and A hears B and stopsstops

B hears A and B hears A and stopsstops

JitterJitter

Occurs when delay changesOccurs when delay changes If the delay increases and decreases If the delay increases and decreases

sporadically it makes conversations sporadically it makes conversations sound choppysound choppy

RTP (Real Time Transport Protocol)RTP (Real Time Transport Protocol) Adds a sequence number and a time Adds a sequence number and a time

stamp to UDP packetsstamp to UDP packets This allows for delay and jitter to be This allows for delay and jitter to be

calculated accurately calculated accurately

Solutions to Jitter and DelaySolutions to Jitter and Delay

Add bandwidth to the entire InternetAdd bandwidth to the entire Internet• We find ways to use up all the bandwidth we We find ways to use up all the bandwidth we

are givenare given Reserve bandwidth on the routers it usesReserve bandwidth on the routers it uses

• This would not be fair to the rest of the packetsThis would not be fair to the rest of the packets Temporary solution is to simply route the Temporary solution is to simply route the

calls through the current switch network.calls through the current switch network.

SIP (Session Initiation Protocol)SIP (Session Initiation Protocol)

Very simple protocol to useVery simple protocol to use Allows for advanced features to be Allows for advanced features to be

applied by the user without a applied by the user without a subscriptionsubscription

FeaturesFeatures

Cheaper Service Cheaper Service No long distance chargesNo long distance charges Caller IDCaller ID Call ForwardingCall Forwarding Call ScreeningCall Screening

• Users can do other things than just Users can do other things than just block a callblock a call

• If Kitrek were to call, I would be able to If Kitrek were to call, I would be able to forward his call to an insult hotlineforward his call to an insult hotline

FeaturesFeatures

VoicemailVoicemail• Check it online with fast-forward, rewind, and Check it online with fast-forward, rewind, and

pausepause• Check it through emailCheck it through email• Check it over the phoneCheck it over the phone

Require unknown callers to provide an Require unknown callers to provide an intent for callingintent for calling• If a telemarketer calls they would have to tell If a telemarketer calls they would have to tell

what they wantedwhat they wanted• It would then be displayed on the caller IDIt would then be displayed on the caller ID

ConclusionConclusion

VoIP is a technology which will VoIP is a technology which will eventually replace the current Switch eventually replace the current Switch network.network.

With new and fully customizable With new and fully customizable features, along with cheaper service features, along with cheaper service and no long distance charges. We and no long distance charges. We can expect to see VoIP much more in can expect to see VoIP much more in the future.the future.

ResourcesResources [1] Danial Collins. (2001). [1] Danial Collins. (2001). Carrier Grade Voice Over IP. Carrier Grade Voice Over IP. New New

York. McGraw-Hill.York. McGraw-Hill. [2] John Shepler. (2005). The Holy Grail of five-nines [2] John Shepler. (2005). The Holy Grail of five-nines

reliability. reliability. Retrieved April 1, 2005 from Retrieved April 1, 2005 from

http://searchnetworking.techtarget.com/generic/0,295582,shttp://searchnetworking.techtarget.com/generic/0,295582,sid7_gci1064318,00.htmlid7_gci1064318,00.html

[3] Tim Lorello, Rich Tehrani (2005). [3] Tim Lorello, Rich Tehrani (2005). E-9-1-1. E-9-1-1. Internet Internet TelephonyTelephony, 8, (3), 40-41. , 8, (3), 40-41.

[4] FCC. (2004) VoIP: FCC Consumer Facts. Retrieved April [4] FCC. (2004) VoIP: FCC Consumer Facts. Retrieved April 1, 2005 from 1, 2005 from http://http://www.fcc.gov/cgb/consumerfacts/voip.pdfwww.fcc.gov/cgb/consumerfacts/voip.pdf

[5] Vonage. (2005) Features. Retrieved April 1, 2005 from[5] Vonage. (2005) Features. Retrieved April 1, 2005 from http://http://www.vonage.com/features.phpwww.vonage.com/features.php