Key Issues in VoIP - Cogeco

Key Issues in VoIPRoger Hay & Associateshttp://www.rogerhay.caVoice Over IP (VoIP) is spreading. What is it, andwhat are the key issues in using and managing it?What is VoIP, Anyway?“VoIP” is voice over the Internet Protocol (IP). IPis the basic protocol for carrying data over theInternet. In VoIP, voice is digitized, the resultingstream of bits is chopped into packets, and thepackets are sent over the Internet using IP. Whenthe packets arrive at their destination, the originaldata stream is reassembled and decoded to recoverthe voice.The Rise of VoIPPeople have been transmitting voice over packetnetworks for at least 20 years. More recently,people have been using the Internet to chat, andnetworks such as Free World Dialup have sprungup to connect them. People have also been usingshared whiteboard, voice and video programs suchas NetMeeting over local area networks and theInternet. These are the harbingers of change.VoIP is now moving into the mainstream andchallenging existing value streams.• A significant and growing portion of lelephonetraffic is shifting to VoIP, and operator andmanufacturer focus has shifted to VoIP.Global wholesale telephone service prices havefallen to a few cents per minute on liberalizedroutes.• Local-area-network (LAN)-based VoIP has allbut taken over the PBX (private branchexchange) world. Enterprises are integratingtheir voice and data networks. Cordless andcellular handsets that use LAN-friendly 802.11WiFi in enterprise environments have emerged.• Old and new service providers, including cableoperators, have started offering VoiP serviceover high-speed access lines.Why is VoIP Becoming Important?VoIP is playing a central role in the trend towardnear-zero telephone service costs and the rise ofproductivity-enhancing applications. Shifting toVoIP may be central to business survival this newenvironment.VoIP allows the end stations to communicatedirectly with each other after being linked up bycentral servers, leading to simpler, more flexibleand more economical networks that support voice,data and video.In the long-distance telephone space, the firstimpetus for VoIP was to bypass high PSTNtermination fees by using the Internet. Now,carriers are looking at the advantages of having asingle, simpler Next Generation Network for voiceand data with lower service-creation hurdles.Enterprises are attracted by only having to manageone set of equipment and wires to the desktoprather than two, being able to combine voice, dataand video on a common wide area network, andmaking practical new productivity tools that thisintegration enables.The growing availability of low-cost high-speeddata access services has opened a way for newlocal and long-distance service providers to reachcustomers using VoIP.Key VoIP Platform ElementsUnless the traffic level is low compared withnetwork bandwidth, typically a quality-controlledand -managed IP network is needed (in contrast tothe raw Internet that only provides a best-effortsservice). In a managed network, voice packets aregiven priority (to minimize jitter and delay),network behaviour under congestion is controlled.Copyright © 2004, 2005 Roger Hay & Associates Ltd.continued …

Key Issues in VoIP (continued)Call detail records may need to be gathered andprocessed. Accurate bills need to be generated andpresented on time, and invoiced charges collected.Economical ways of doing this at a small fractionof a cent per minute of use are needed.Productive centralized operations, maintenance,administration and provisioning tools are needed.Business plans are needed which re-align and bringtogether the new regulatory and competitivelandscapes, markets, segments, bundles, prices,channels, platforms, operations, settlements,billing, collections, finances and profits.Protocols in VoIPIn carrier networks, the emerging standard forVoIP is SIP (Session Initiation Protocol).The ITU-T H.323 suite of standards is common onlocal area networks, and is supported by manyPBXs and used by applications such asNetmeeting.MGCP (Media Gateway Control Protocol) is usedto control interworking devices at the edges of themanaged IP networkMarket Structure, Technical and RegulatoryIssuesThe old market and regulatory structure ischanging. Voice service prices have fallen to thepoint where, on liberalized routes, charges set byregulators to defray local incumbent service costsnow dominate regardless of distance, increasingthe pressure on the “last mile” cost bottleneck.VoIP is playing a central role. How theopportunities and challenges are addressed by newentrants, incumbents, manufacturers and regulatorswill decide the new market and regulatorystructure.Select the right codec(s). Some high compressionalgorithms, that squeeze voice into a low bit rate tosave bandwidth, sound bad and introduce delay,and should be avoidedVoice dislikes jitter. Jitter is rapid changes in thetransit delay between speaker and listener. A lowdelaytransport network, and buffering at thereceive end, are needed.Voice dislikes delay. Delays of more than about100 milliseconds will interfere with conversation.In VoIP, low-bit-rate encoding and IP queuingdelays can easily build up to this amount andbeyond, so it is important to manage encoding anddelay within acceptable limits.Voice dislikes echo. Virtually all of the telephoneson the public switched telephone network are twowire,which means that some of the receivedspeech energy gets reflected back to the talker asecho. Users find delayed echoes highlyobjectionable. For delays typical of VoIP, echocancelling is needed.Excessive transcoding degrades voice. If there aretoo many conversions from one voice encodingstandard to another in a call (including voice mailrecording and playback), the resulting sound isdistorted, so the total quantity of transcodings inthe speech path must be managed.Legal wiretapping may impact economics. One ofthe advantages of SIP is that it allows end stationsto talk directly to each other after call setup. If itturns out that central servers must remain in thecall after setup in order to do legal wiretapping,then this may impact the economics of VoIP.For further information, please contactRoger Hayroger@rogerhay.caTelephone +1 (905) 616-4429Roger Hay & Associates1272 Elgin CrescentOakville, Ontario, Canada L6H 2J7Tel +1-905-616-4429http://www.rogerhay.caE-mail info@rogerhay.ca