Internet TelephonyWhat will be covered?What is Internet Telephony?Traditional Phone LinesData NetworksCost ComparisonGatewaysProtocols4 Ways of using VoIP4 Ways of using VoIP (cont.)Slide 11Slide 12Internet TelephonyInternet TelephonyPresentedPresentedByByDonna WilliamsDonna WilliamsWhat will be covered?What will be covered?What is Internet Telephony?What is Internet Telephony?How does it work?How does it work?Cost ComparisonCost ComparisonGatewaysGatewaysProtocols Protocols 4 Ways of using VoIP4 Ways of using VoIPWhat is Internet What is Internet Telephony?Telephony?Is the transmission of telephone calls Is the transmission of telephone calls over a data networkover a data networkKnown in the industry as VoIP (Voice Known in the industry as VoIP (Voice over IP) over IP) Many traditional telephone companies Many traditional telephone companies are already using it in the connections are already using it in the connections between their regional offices.between their regional offices.Traditional Phone LinesTraditional Phone LinesCircuit SwitchingCircuit SwitchingIn use for over 100 years.In use for over 100 years.When a call is made, the connection is When a call is made, the connection is maintained for the entire duration of a call.maintained for the entire duration of a call.This connection is called a This connection is called a circuitcircuit..Foundation of the Public Switched Foundation of the Public Switched Telephone Network (PSTN).Telephone Network (PSTN).http://computer.howstuffworks.com/ip-tehttp://computer.howstuffworks.com/ip-telephony1.htmlephony1.htmData NetworksData NetworksUse a method called Use a method called packet switchingpacket switching..Connection is opened up just long enough to send a Connection is opened up just long enough to send a small chunk of data, called a small chunk of data, called a packetpacket, from one system , from one system to another.to another.EfficientEfficientMinimizes the time that a connection is maintained between Minimizes the time that a connection is maintained between two systems, which reduces the load on the network.two systems, which reduces the load on the network.It also frees up the two computers communicating with each It also frees up the two computers communicating with each other so that they can accept information from other other so that they can accept information from other computers as well.computers as well.http://computer.howstuffworks.com/ip-telephony2.http://computer.howstuffworks.com/ip-telephony2.htmhtmCost ComparisonCost ComparisonCircuit SwitchingCircuit Switching Fixed rate of 64 kilobits per Fixed rate of 64 kilobits per second (Kbps) or 1,024 second (Kbps) or 1,024 bits per second in each bits per second in each direction for total direction for total transmission rate of 128 transmission rate of 128 Kbps.Kbps.8 kilobits (Kb) in a kilobyte 8 kilobits (Kb) in a kilobyte (KB) (KB) 16 KB each second 16 KB each second 960 KB each minute960 KB each minute10 min conversation = 10 min conversation = 9600 KB or 9.4 megabytes 9600 KB or 9.4 megabytes (MB)(MB)4.7 MB of dead air4.7 MB of dead airPacket SwitchingPacket Switching10 min conversation uses 10 min conversation uses only 3.5 minutes of only 3.5 minutes of transmission time at a transmission time at a cost of 64 Kbpscost of 64 Kbps64 Kbps free + additional 64 Kbps free + additional 128 Kbps for the 128 Kbps for the remaining 6.5 minutesremaining 6.5 minutesData CompressionData CompressionGatewaysGatewaysUsed to connect devices on two different types Used to connect devices on two different types of networks so that they can communicate with of networks so that they can communicate with each other.each other.It converts the circuit-switched signals from It converts the circuit-switched signals from each phone into digital data that can be sent each phone into digital data that can be sent over a packet-switched, IP-based network.over a packet-switched, IP-based network.You need a digital PBX (private branch You need a digital PBX (private branch exchange) to use this.exchange) to use this.Some companies on the internet will provide Some companies on the internet will provide this service (i.e. Net2Phone.com, Dialpad.com, this service (i.e. Net2Phone.com, Dialpad.com, Vonage.com, Vocaltec.com).Vonage.com, Vocaltec.com).ProtocolsProtocolsTwo major protocols used for VoIPTwo major protocols used for VoIPH.323H.323 – Standard created by International Telecommunications Union (ITU). – Standard created by International Telecommunications Union (ITU).Comprehensive and very complex protocol.Comprehensive and very complex protocol.Provides specifications for real-time, interactive videoconferencing, data Provides specifications for real-time, interactive videoconferencing, data sharing and audio applications.sharing and audio applications.Cons – requires a lot of overhead.Cons – requires a lot of overhead.Session Initiation Protocol (SIP)Session Initiation Protocol (SIP) – Under the auspices of the Internet – Under the auspices of the Internet Engineering Task Force (IETF).Engineering Task Force (IETF).Streamlined protocol developed specifically for IP Telephony.Streamlined protocol developed specifically for IP Telephony.Smaller and more efficient than H.323, SIP takes advantage of existing Smaller and more efficient than H.323, SIP takes advantage of existing protocols to handle certain parts of the process.protocols to handle certain parts of the process.Media Gateway Control Protocol (MGCP) is used by SIP to establish a Media Gateway Control Protocol (MGCP) is used by SIP to establish a gateway to the PSTN system.gateway to the PSTN system.4 Ways of using VoIP4 Ways of using VoIPComputer-to-computerComputer-to-computerEasiest way.Easiest way.No charge for long distance calls.No charge for long distance calls.All you need is the software, a microphone, All you need is the software, a microphone, speakers, a sound card, and an Internet speakers, a sound card, and an Internet connection for both parties.connection for both parties.Internet connection – Should use cable or Internet connection – Should use cable or DSL modem.DSL modem.Software example: MSN ExplorerSoftware example: MSN Explorer4 Ways of using VoIP 4 Ways of using VoIP