Chapter 17 Voice over IPObjectivesObjectives (continued)VoIPVoice over the InternetVoIP ProtocolsVoIP Protocols (continued)Signaling ProtocolsSession Initiation ProtocolSession Initiation Protocol (continued)SIP FunctionsH.323VoIP Transport ProtocolsReal-Time Transport ProtocolImplementation OptionsSoft PhonesSoft Phones (continued)Slide 18Analog Telephony AdaptersAnalog Telephony Adapters (continued)IP Phones and Wi-Fi PhonesIP Phones and Wi-Fi Phones (continued)IP PhoneWi-Fi PhonesSlide 25Residential Broadband VoIP ServicesSlide 27Residential Broadband VoIP Services (continued)Business VoIP OptionsBusiness VoIP Options (continued)Private IP NetworkInternet Telephony BenefitsCost SavingsCost Savings (continued)Unified CommunicationsSummary of Business VoIP DriversInternet Telephony ChallengesQuality of Service (QoS)Power OutagesUninterruptible Power Supply (UPS)ReliabilityReliability (continued)VoIP SecurityPublic Policy IssuesPublic SafetyPublic Safety (continued)Regulatory Jurisdiction & TaxationSummarySummary (continued)Slide 50Chapter 17Voice over IPInformation Technology in TheoryBy Pelin Aksoy and Laura DeNardis2Objectives•Understand the concept of VoIP and how it enables the transmission of voice over the Internet•Gain familiarity with VoIP protocols such as SIP, H.323, and RTP•Understand options for implementing voice over the InternetInformation Technology in Theory3Objectives (continued)•Recognize the business drivers and advantages of using VoIP rather than traditional telephone system architectures•Understand the security and performance challenges of VoIP and consider various solutions•Identify the policy questions arising from the proliferation of VoIP servicesInformation Technology in Theory4VoIP•VoIP = Voice over Internet Protocol–Also called Internet telephony or IP telephony–Refers to voice communications transmitted over the Internet or other IP network, as opposed to the public switched telephone networkInformation Technology in Theory5Voice over the Internet•Many businesses, institutions, and individual users place telephone calls over the Internet –Rather than through a traditional telephone network, completely bypassing the circuit-switching approach of the telephone system •A VoIP call does not necessarily remain solely on the Internet or other TCP/IP network•Uses packet switching, not circuit switchingInformation Technology in Theory6VoIP Protocols•A set of standards designed for transmitting voice calls over the Internet or other IP network •VoIP calls have several functional components:–The signaling information that establishes the telephone call–The process that digitizes the audio signal and places the information into packets–The process of actually transmitting the packetized speechInformation Technology in Theory7VoIP Protocols (continued)Voice communication over the InternetInformation Technology in Theory8Signaling Protocols•Signaling protocols assess user availability, ring the destination device, establish a call, and terminate a call session•Two of the most well-known VoIP signaling protocols: –The Session Initiation Protocol (SIP), developed by the IETF–H.323, a family of standards developed by the ITUInformation Technology in Theory9Session Initiation Protocol•SIP is a signaling protocol that creates, manages, and terminates multimedia sessions between end-user devices, such as two telephones•A session is a voice conversation or other exchange of information between users •SIP operates at the Application layer of the OSI model using an information exchange that is similar to HTTPInformation Technology in Theory10Session Initiation Protocol (continued)Establishment of a VoIP session using SIPInformation Technology in Theory11SIP Functions•End-user location—Find the end-user location with which to communicate•End-user availability—Determine whether the end user is available and willing to engage in conversation•End-user capability—Determine what type of media content will be used and what constraints might be in effect•Session setup—Establish the session between parties (also called “ringing”)•Session management—Handle changes to the communication session while the call is in process and terminate the session upon completionInformation Technology in Theory12H.323•An ITU-developed signaling standard for multimedia communications over the Internet and other IP networks•The first widely implemented signaling protocol that supported real-time voice and video over IP networks•Strictly speaking, H.323 is actually a series of many protocols Information Technology in Theory13VoIP Transport Protocols•Handle the transmission of the voice call between endpoints•Real-time Transport Protocol (RTP) is a popular VoIP transport protocolInformation Technology in Theory14Real-Time Transport Protocol•Known by its acronym, RTP•Establishes the standard for end-to-end transmissions that carry actual digitized speech in packets•Designed to transport voice, video, and other information that have real-time propertiesInformation Technology in Theory15Implementation Options•Soft phones•Analog telephony adapters•IP phones•Wi-Fi phones•Residential VoIP offerings•Business VoIP alternativesInformation Technology in Theory16Soft Phones•Install VoIP software on a computer and use it with a headset to make a voice call•Requires:–Headset (or microphone and speakers)–Sound card–Freely available VoIP software–Broadband Internet connection Information Technology in Theory17Soft Phones (continued)Computer-to-computer Internet telephony with soft phonesInformation Technology in Theory18Soft Phones (continued)Computer-to-computer Internet telephony via cordless telephoneInformation Technology in Theory19Analog Telephony Adapters•This device serves as an analog-to-digital converter (ADC) between an analog phone and an Ethernet network connection to an IP network•Other analog devices, like fax machines, can also be plugged into the ATA•This option does not require the installation of VoIP software on a computerInformation Technology in Theory20Analog Telephony Adapters (continued)Information Technology in Theory21IP Phones and Wi-Fi Phones•An IP phone connects directly to an IP network without an adapter because it internally converts the telephone audio signal into digital format for transmission over the IP network –Has the same features traditional phones