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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