Voice over IP for Carriers Agenda t

Voice over IP for Carriers

Agenda t Advantages of packet switching for voice communications t Vo. IP applications t Vo. IP technology overview t Vo. IP standards t Quality-of-Service in Vo. IP networks t Addressability in Vo. IP networks t Vo. IP regulatory considerations All rights reserved © 2001, Alcatel

What is Vo. IP? t Technical answer: “the ability to make phone calls over IP-based data network” t Commercial answer: ”the Multi-Billion Revenue Opportunity for the 21 st Century” t Vo. IP > IP Telephony t typically “IP Telephony” indicates using IP terminals t most Vo. IP is between normal telephones t Vo. IP < “Voice over Packet” t includes Voice over Frame Relay, ATM All rights reserved © 2001, Alcatel

Circuit switching served voice well for 100 years! Signal System 7 Data link Signal Transfer Point Trunk Group Loop User - A Class 5 Switching System User - B Central Office - A Transit Office Connection Through Switching Fabric Central Office - B Class 4 Switching System t Transmission circuits and switch path assigned during call setup for the duration of the call t Call blocks if not enough network resources available t Essentially one class of service: 3. 5 k. Hz, 64 kb/s t Poorly matched for bursty data transmission All rights reserved © 2001, Alcatel

Packet Switching Well-matched for data transmission Packet Payload Header Input Buffer Hdr. Trans Routing Fabric Output Buffer Hdr. Trans t t t Great fit for bursty data transmission! Packets sent at full rate of transmission facility Supports variable information transfer rates Resources not consumed when nothing to send Potential to eliminate call setup phase t But … t Transmission capacity used for header t Buffering introduces varying delays All rights reserved © 2001, Alcatel

Vo. IP Network Architecture Signaling Gateway Media Gateway Controller PSTN network IP network Media Gateway t Media gateways provide voice packetization t Media gateway controller provides call control logic t Signaling gateway provides interworking with SS 7 signaling of PSTN All rights reserved © 2001, Alcatel

Advantages of Vo. IP t Regulatory arbitrage (e. g. , lack of access charges) t Low entry barrier competition with incumbent carriers t Cheaper switching systems t Per Gb/s, IP routers cheaper than TDM Class 5 switching systems t Ability to operate one network for voice and data t Cost savings through use of low-bit-rate voice t Ability to offer more complex services t E. g. , Multimedia, multiport calls t Intelligent terminals (e. g. , PC) t Better (graphical) user interface t Clean slate design: t Separation of feature intelligence from switching fabric supplier t Self-provisioning networks All rights reserved © 2001, Alcatel

PSTN Vs Vo. IP Network Costs t Network costs (transmission and switching costs) contribute only 10 -15 % of overall cost of a voice call terminated by an ILEC or a PTT, and 20 -30% of overall costs for calls not terminated by a ILEC or a PTT t Of the network costs, switching costs range between 50 % of network costs for domestic calls to 15 % of network costs for international calls, transmission costs contributing the rest t Negligible savings in transmission costs through the use of Vo. IP: lower bandwidth for Vo. IP offset by need for overprovisioning bandwidth to ensure quality t TDM Switch costs in traditional PSTN replaced by cost of Router plus cost of Gateway [GW] plus cost of Gateway Controller [GWC] plus cost of new OSS/NMS/Billing /Provisioning No network cost savings, and very likely a cost penalty, in the initial years, in going from PSTN voice to Vo. IP for public networks All rights reserved © 2001, Alcatel

PSTN versus Vo. IP Today’s PSTN Vo. IP TDM circuit switching Packet switching Qo. S guarantees Yes No Network resource reserved at call setup Yes No Network elements Class 4, Class 5 switching systems Gateways, gateway controllers, routers Call processing intelligence Mostly integrated in switching system In separate gateway controllers 64 kb/s Variable 8 – 32 kb/s Signaling DTMF, SS 7 SIP, H. 323 Transport TDM in access, edge, core ATM, FR, native IP in access; ATM native IP in core Redundancy within each network element Redundant routes through network Underlying Technology Bandwidth per call How reliability achieved All rights reserved © 2001, Alcatel

Vo. IP versus Voice-over-the-Internet t No bandwidth guarantees t No prioritization of traffic within network t All traffic receives “best effort” service t Each Internet user is at the mercy of all other users t Voice quality ranges from acceptable to atrocious However t Internet technology continues to evolve (e. g. , IPv 6) t Development of Next Generation Internet All rights reserved © 2001, Alcatel

What does “Carrier Grade” really mean? t “Five 9’s” reliability (down time of 5 minutes a year) t Full redundancy of electronics, power supplies, fans, etc. t No down time for upgrades or maintenance t Accounting and billing capabilities t Interoperability with legacy telecommunications equipment t Feature parity with equipment it replaces t Service quality measurements t Support for CALEA, unbundling, and other governmental mandates t NEBS compliance for operation in central offices t Both safety and performance requirements t Scalability to millions of subscribers t Integration into the myriad of Operations Support Systems All rights reserved © 2001, Alcatel

Vo. IP market Voice over Internet Protocol (Vo. IP) gateway sales will increase 280 percent during the next five years, reaching $3. 8 billion in 2003, according to research by Cahners In-Stat Group. FORECASTED TO GROW IP TELEPHONY OVER LAN MARKET 138% AVERAGE ANNUALLY OVER NEXT 5 YEARS September 22, 1999 - IP Telephony [IP PABXes], according to a study from The Phillips Group-Info. Tech, will spawn a $1. 9 billion industry by the year 2004 with an average annual industry growth of 138 percent over the next 5 years. IDC Forecasts IP Telephony Market Will Soar to 2. 7 Billion Minutes of Use and $480 Million in Revenues by Year end 1999 Business Use Will Accelerate in 2001 September 1, 1999 - The worldwide Internet protocol (IP) telephony will explode from 310 million minutes of use in 1998 to 2. 7 billion by year end 1999. By 2004, IP telephony minutes will reach 135 billion. Revenues for this service will skyrocket from $480 million in 1999 to $19 billion by 2004. IP Telephony Services: Market Review and Forecast, 1998 -2004. All rights reserved © 2001, Alcatel

Growth in Vo. IP t Early growth from expense savings t Later growth from revenue generation from new services t Early deployment by enterprises and CLECs t Later deployment by incumbent carriers (source: Frost & Sullivan) All rights reserved © 2001, Alcatel

Vo. IP Applications t Some trends can be discerned: t First wave: Bypassing the PSTN t Second wave: Replacing the PSTN t Third wave: Value-added services PSTN DLC Class 5 DLC All rights reserved © 2001, Alcatel

PSTN bypass – IP Telephony (PC to PC) t Microsoft Net. Meeting or similar t through dial-up connection to ISP t All Vo. IP processing in the PC t no special infrastructure required t Issues: t software compatibility t Qo. S / latency over public Internet RADIUS server Internet modem DLC Class 5 RAS modem Class 5 DLC All rights reserved © 2001, Alcatel

PSTN bypass – IP Telephony (PC to phone) t From Multimedia PC to any phone t Required: t Vo. IP gateway on the phone side t gateway manager t billing system (unless free) t Issues: t software compatibility t Qo. S / latency over public Internet RADIUS server Gate Keeper Internet modem DLC Class 5 RAS Vo. IP Gateway Class 5 DLC All rights reserved © 2001, Alcatel

PSTN bypass – IP Telephony (phone to phone) t From any phone to any phone t First Vo. IP application – 1995 t Caused by high international tariffs t Required: t Vo. IP gateway on both sides t gateway manager t billing system (unless free) t Issues: t Qo. S / latency over public Internet t sometimes it takes 24 digits to reach a subscriber… Gate Keeper DLC Class 5 Vo. IP Gateway IP network Vo. IP Gateway Class 5 DLC All rights reserved © 2001, Alcatel

PSTN bypass – Enterprise gateway t Link PABXes on company sites through data network t first Voice over Frame Relay, next Voice over IP t Required: t Vo. IP gateway at each site t sometimes integrated in WAN router t Issues: t dial plan configuration not easy! PABX Vo. IP Gateway IP network Vo. IP Gateway PABX PSTN All rights reserved © 2001, Alcatel

PSTN bypass – IP PABX t Two steps: t A. PABX with integrated IP gateway t B. Fully integrated enterprise LAN t Required: t IP PABX t IP phones (step 2) t Issues: t dial plan configuration not easy! t how to quarantee Qo. S on LAN? (step 2) A B IP network IP-PABX IP-phone PSTN All rights reserved © 2001, Alcatel

PSTN replacement – Softswitch t Replace complete Class 4 / Class 5 switch t very ambitious undertaking! t different introduction strategies t Required t Softswitch - contains Call Control & Mgmt software t Trunking Gateway – interfaces to “legacy” PSTN t Access Gateway – interfaces to DLCs t Issues: t immaturity of standards (MGCP vs Megaco debate) Soft switch DLC Class 5 Trunking Gateway IP network Access Gateway DLC All rights reserved © 2001, Alcatel

PSTN replacement – Integrated access network t Integrating Access Gateway into DLC t Required: t “Next Gen” DLC, with integrated IP gateway t Issues: t immaturity of standards Soft switch IP network Nex. Gen DLC All rights reserved © 2001, Alcatel

PSTN replacement – Integrated Access Devices t Target: single voice/data access network t for example wireless access network (LMDS, WLL) t Required: t Integrated Access Device (IAD) t gateway to PSTN t Issues: t immaturity of standards Integrated Access Device Gate Soft Keeper switch Vo. IP Gateway IP PSTN network Class 5 All rights reserved © 2001, Alcatel

Value Added Services t Converged services t Internet Call Waiting t Click to Call t Unified messaging t … t Video telephony (3 rd time right? ) All rights reserved © 2001, Alcatel

Application Scenario t Mike Brown uses his Palm XIXv for voice calls and Internet access. He subscribes to “Mobile Web” from Verizon Wireless. t Mike is wallpapering, but has some trouble. He calls Home Depot for help. t Mike reaches Home Depot’s IVR and is greeted with the following: “Hi Mike, welcome back to Home Depot, the only choice you need in home improvement supplies and help. Press 0 at any time to speak with an operator. To help with you home improvement needs, we have created a number of short videos which are available free of charge to Preferred Customers such as yourself. To access the video library, say ‘Video’. Otherwise, please say ‘Sales’ for sales; ‘Delivery’ to schedule a delivery; “’Service’ for Customer Service, or ‘Message’ to leave a message. Have a great day. ” t Mike mumbles ‘Video’. All rights reserved © 2001, Alcatel

Application Scenario (Cont. ) t Announcement “Welcome to Home Depot’s video library. Our t t database indicates you have a Palm. Phone so we will play the streamed video. Please say ‘email’ if you prefer the video as email attachment. [short silence] Please make your selection from the following list of home improvement videos by pressing the corresponding number at any time. 1 for hardwood floors, 2 for interior painting, 3 for wallpapering, 4 for outside lighting” Mike says ‘ 3’. Announcement: “Thank You. We hope the video on wallpapering is helpful. Please press ‘video’ on your screen, and your video should start within a few seconds. Have a great day. ” Mike presses “play video” on the Palm. Phone screen. Video starts (advertising opportunity/branding opportunity, with hotlinks back to Home Depot site and context-sensitive buttons to contact product specialists). All rights reserved © 2001, Alcatel

Standards for Vo. IP

The H. 323 Protocol Stack System control user interface H. 225 RAS channel Q. 931 call setup H. 245 control Camera Audio And Video Control RTCP Data applications Video Codec H. 261 H. 263 Mic T. 120 Audio codec G. 711 G. 723 G. 729 RTP Transport Layer (TCP or UTP) IP All rights reserved © 2001, Alcatel

Real-Time Transport Protocol V=2 P X CC M PT Sequence Number Timestamp Synchronization Source Identifier Contributing Source Identifiers (0 to 15 entries) P – Padding X – Extension CC – Contribution source count M – Marker (for silence suppression) PT – Payload type t Developed by IETF t Provides end-to-end delivery services for data with real-time characteristics such as interactive audio and video. t Supports a wide variety of fixed and variable-speed audio and video signals t Applications typically run RTP on top of UTP t Supports multicast distribution All rights reserved © 2001, Alcatel

RTP Control Protocol (RTCP) V=2 P PT=SR=200 Length SSRC of sender NTP Timestamp (Network time) NTP Timestamp RTP Timestamp (Network time in RTP units) Sender’s packet count Sender’s octet count SSRC of first cource Fraction lost Cumulative number of packets lost Extended highest sequence number received Interarrival jitter Last SR Delay since last SR t t Sent from receiver back to source Used to monitor the quality of service Feedback allows modifications to be made at source 5 percent of session bandwidth allocated to RTCP All rights reserved © 2001, Alcatel

H. 225 RAS Control Gatekeeper Endpoint H. 225 Multiport Control Unit Gateway t Gatekeeper t Optional network entity t Offers bandwidth control services t Offers address translation to enable use of aliases t H. 225 t Operates between a Gatekeeper and the endpoints it controls t Provides functions of discovery, registration, admission, bandwidth change, disengage All rights reserved © 2001, Alcatel

Call Signaling in H. 232 Q. 931 H. 245 t Q. 931 t Establishes and tears down calls between endpoints t (Q. 931 is the signaling protocol for the ISDN user-network interface) t H. 245 t Negotiates and establishes media streams between call participants t Takes care of multiplexing multiple media streams for functions such as lip synchronization between audio and video All rights reserved © 2001, Alcatel

Session Initiation Protocol (SIP) t User to user protocol t Developed by IETF (RFC 2543) t Establishes and maintains session level information t Creating and tearing down of sessions, session parameters, and media type t Supports personal mobility t Heavily influenced by http protocol t A light weight protocol compared to H. 323 t Fewer messages required on a typical call t Allows for faster call setup t Flexible in enabling other information to be included messages t Allows user devices to exchange specialized information to enable new services t E. g. , indicate when a busy terminal will become free t Example SIP addressing; sip: 9729965000@gateway All rights reserved © 2001, Alcatel

Internet call processing t Decentralized (independent, self-reliant, user to user): t ITU H. 323 t IETF Session Initiation Protocol (SIP) t Centralized (intelligence in Softswitch): t IETF MEGACO t ITU H. 248 All rights reserved © 2001, Alcatel

Softswitch Architecture To other Softswitches SIP-T MGCP Or Megaco Softswitch IP Network Access Gateway PSTN Network Trunk Gateway t Softswitch separates function of Gateway from the media gateway All rights reserved © 2001, Alcatel

ATM Qo. S Parameters t Peak-to-peak cell delay variation t Maximum cell transfer delay Negotiated at start of call t Cell loss ratio t Cell error ratio t Severely errored cell block ratio Controlled via Network design t Cell misinsertion rate All rights reserved © 2001, Alcatel

Real-Time Multimedia over ATM (RMOA) PSTN Switch H. 323 Gateway Vo. IP Gateway IP Network ATM network H. 323 Gateway PSTN Switch Vo. IP Gateway t Developed by ATM Forum t More efficient and scalable than H. 323 Vo. IP over ATM t New type of gateway: the H. 323 to H. 323 gateway t Placed at the edges of an ATM network t Intercepts H. 323 signaling messages to set up virtual circuits in the ATM network t Efficient: IP and UDP headers not carried on the ATM network t Takes advantage of Qo. S capabilities of the ATM network All rights reserved © 2001, Alcatel

Resource Reservation Protocol (RSVP) Host RSVP Process Application Control Router Policy Control Routing Process RSVP Process Control Admission Control Packet Classifier Packet Scheduler Policy Control Admission Control Packet Classifier Packet Scheduler t Specified in RFC 2215 t Reserves resources along path from received back to sender t Implements various services t Guaranteed service – no packet loss and minimal delay t Controlled load service – service like a lightly loaded network t Number of parameters associated with each service t Comprehensive, close to circuit emulation, but at significant cost All rights reserved © 2001, Alcatel

Adding Qo. S to IP Networks: Diffserv Meter Classifier Marker Shaper / Dropper t Relatively simple means for prioritization traffic (RFC 2475) t Makes use of the IPv 4 Type of Service (TOS) field t Defines two types of packet forwarding: t Expedited Forwarding – assigns a minimum departure rates greater than the per-agreed maximum arrival rate t Assured Forwarding – packets are forwarded with high probability if arrive no faster that per-agreed maximum t Keeps core relatively simple t Pushes processing to the edge All rights reserved © 2001, Alcatel

Vo. IP access via DSL and Cable Modems

Cable Telephony Video Content Internet Service Head end Fiber Node PSTN Gateway t Where to put the RJ-11 telephone jack? t t t On cable modem On set-top box On separate telephony modem On interface on side of house Local powering or network powering options

What is DOCSIS? (Data Over Cable System Interface Specifications) t Started 12/95 by MCNS consortium (Multimedia Cable Network System) t Goal: Interoperable cable modems and Cable Modem Termination Systems (CMTS) t Steamed rolled slower (ATM-based) IEEE 802. 14 standardization process t Gaining momentum in Europe as Euro. DOCSIS (8 MHz channelization) t Testing and certification by Cable Labs

Who are the DOCSIS Cable Modem Suppliers? t t t t 3 Com Ambit Arris Interactive Askey Computer Corp. Best Data Castlenet Cisco Systems Com 21 Dassault Delta. Kable DX Antenna ELSA E-Tech Future Networks Gad. Line Toshiba t t t t Turbocom General Instrument GVC Joohong Motorola Net N Sys Nortel Philips Powercom Samsung Sohoware Sony Tarayon Thomson Zoom Zy. Xel

Cable Modems More suppliers, lower prices 5 Suppliers 32 Suppliers

What is Packet Cable? t Network specification by Cable Labs t Based on DOCSIS 1. 1 t Support for voice services t Complete network architecture specification t First using GR 303 gateways (to legacy telephone networks) t Evolving to Softswitch (next generation IP networks) t Trials underway

Cable. Labs Packet Cable Architecture Call Management Server (CMS) MTA Cable Modem HFC Access Network (DOCSIS) Announcement Server Announcement Controller (ANC) CMTS Announcement Player (ANP) Managed IP Network MTA Cable Modem HFC Access Network (DOCSIS) CMTS Media Gateway Controller (MGC) Media Gateway (MG) Signaling Gateway (ANP) OSS Back Office Servers and Applications PSTN

Status of Vo. IP over Cable t Cable executive panel at Cable 2001 (June 11, 2001): t Most cable operators will not roll out significant Vo. IP until at least the end of 2002 t Concerned about the operational issues that come with providing a voice service t General agreement that Vo. IP economics work in their favor if combined with existing cable services t Some view Vo. IP as primary line replacement; others (e. g. , Time Warner) as second line service All rights reserved © 2001, Alcatel

North America Cable Telephony Market Size t Cable projected to capture 15 % telephony market share by 2005 t Shift from proprietary TDM solutions towards Vo. IP DOCSIS t Residential Vo. IP happening first in the Cable Access Market

Voice over DSL CO PSTN CO / CEV GR 303 Voice Gate Way Data Network HOME/BUSINESS ADSL DS 3 / OC-3 Class 5 Switch 4 -16 ATM Switch 1 VC for Voice 1 VC for Data DSLAM LAN Integrated Access Device t Integrated Access Device (IAD) provides LAN interface and provides multiple telephone interfaces t IAD could be integrated into NID at side of the home t Voice Gateway provides same switch interface as though lines were concentrated on a Digital Loop Carrier system t GR 303 allows for number portability, billing and additional voice features All rights reserved © 2001, Alcatel

Alternatives for Vo. DSL Voice over ADSL Alternatives • Voice over IP IP Layer 3 • Voice over ATM Layer 2 • Voice over TDM DMT Layer 1 • Voice in separate spectrum (e. g. , ADSL over DAML) Analog Spectrum t Choice of Voice over ATM in initial implementations – AAL-2 – Low-delay, clear 64 kb/s PCM and 32 kb/s ADPCM – Qo. S support within ATM – Full PSTN quality – V. 90 modem support t Support for Voice over IP gaining momentum t Maturing of Qo. S capabilities t Potential of IAD becoming a SIP terminal All rights reserved © 2001, Alcatel

Quality issues for the transport of voice over packet-based networks

The three essential stages of packet-based voice transport one-way Mouth-to-Ear (M 2 E) delay overall distortion (codec & packet loss) (Concatenation of) Packet-based Network(s) Encoding and packetization stage Packet transport stage Dejittering and decoding stage Echo control performed close to destination

Components of the M 2 E delay Packetization delay Total minimal delay Total queuing delay Dejittering delay M 2 E delay t Packetization delay is chosen by the source terminal or ingress GW t Minimal delay and queuing delay depend on Qo. S provided by traversed network(s) t Each network component has its specific contribution t Dejittering delay is chosen by the destination terminal or egress GW

Trade-off M 2 E delay vs. packet loss in destination or egress GW Pdf(delay) Dejittering delay Packet loss Minimal Delay of delay first packet M 2 E delay t Static dejittering mechanism = delay first packet over dejittering delay and then read dejittering buffer periodically t Choose dejittering delay on save side: for the case when first packet is the fastest possible t Adaptive dejittering All rights reserved © 2001, Alcatel

Contributions to distortion t Voice compression t encoding/decoding t voice activity detection t transcoding t Packet loss t in network t in dejittering buffer t Remarks t packet loss concealment techniques t trade-off packet loss vs. delay when choosing the dejittering delay

Trade-offs Network (transport) parameters t minimal delay t delay jitter t packet loss Echo control Dejittering delay Voice quality Packet size Codec Header compression Efficiency of transport

The E-model ITU-T Rec. G. 107 Objective network parameters Basic signal-tonoise ratio Impairments which occur caused by Distortion impairment simultaneously delay with voice signal Advantage factor E-model R = R 0 - Is - Id - Ie + A Rating Factor in [0, 100] Predictions of user reactions: Subjective quality measures Mean Opinion Score (MOS) All rights reserved © 2001, Alcatel

Subjective quality of a voice communication Defined quality categories in ITU-T Rec. G. 109 PSTN quality GSM quality

The E-model in the context of Vo. P t In the transport of Voice over Packet-based (Vo. P) Networks t M 2 E delay t distortion is likely to be higher, t acoustic echo may be more important and 4 -to-2 -wire hybrid echo might be different than in circuit-switched voice transport t With the E-model we determine (the influence of Id and Ie) R = f ( M 2 E delay, level of echo ; codec(s), packet loss) t We do not consider influence of Ro , Is and A as their influence is not fundamentally different in packet-based and circuit switched transport All rights reserved © 2001, Alcatel

Influence of distortion R = f ( M 2 E delay, level of echo ; codec(s), packet loss) t Intrinsic rating Rint = rating for a M 2 E delay of 0 ms t In the context of Vo. IP, there are two impairments that mainly hamper the quality of a voice call ¬ The impairment Ie associated with the use of “special equipment” or distortion t Coding t Packet loss t Transcoding The impairment Id associated with the M 2 E delay All rights reserved © 2001, Alcatel

Speech Coding Techniques t Waveform coding – Tries to preserve the time-domain picture of the signal t Sampling – 2 X highest frequency preserved t Quantizing – the accuracy of each sample t Linear – simple digital / analog conversion t Logarithmic – more accuracy for weak signals t Adaptive – match measurement to size of signal t Sounds great at high bit rates but degrades quickly at lower bit rates t Vocoding – Tries to represent the characteristics of the human voice t Prametric Vocoders t Dozen coefficients to define vocal tract t Indication of voiced or unvoiced t Excitation energy t Pitch t Synthetic sounding at all bit rates but works OK at low bit rates t Vector Quanitization – Matches information signal with entries in a code book. t Uses lots of processing power but provides the best quality at lower bit rates All rights reserved © 2001, Alcatel

Major Parameters of Standard Codecs Standard Type Codec Bit rate G. 711 Origin PCM G. 726 G. 727 ADPCM 24 12. 8 G. 728 LD-CELP G. 729(a) CS-ACELP 8 ACELP 5. 3 MP-MLQ 6. 3 GSM-FR RPE-LTP GSM-SR GSM-ESR G. 723. 1 0. 125 16 0. 125 0. 625 0 0. 625 10 5 15 Intrinsic quality 94. 3 50 44. 3 25 69. 3 7 0 le 0 0. 125 Algor. delay (ms) 32 40 ITU-T ETSI Look ahead (ms) 64 16 Voice Frame (ms) 87. 3 2 92. 3 20 74. 3 7 87. 3 10 84. 3 19 75. 3 15 79. 3 30 7. 5 37. 5 13 20 0 20 20 74. 3 VSEPL 5. 6 20 0 20 23 71. 3 ACEPL 12. 2 20 0 20 5 89. 3 All rights reserved © 2001, Alcatel

Intrinsic quality of codecs as function of their bit rate All rights reserved © 2001, Alcatel

Influence of packet loss on distortion All rights reserved © 2001, Alcatel

Transcoding matrix t Transcoding is the translation of one codec format into another (via the linearly quantized 8 k. Hz sampled voice format) All rights reserved © 2001, Alcatel

Influence of M 2 E delay R = f ( M 2 E delay, level of echo ; codec(s), packet loss) t In the context of Vo. IP, there are two impairments that mainly hamper the quality of a voice call ¬ The impairment Ie associated with the use of “special equipment” or distortion The impairment Id associated with the M 2 E delay t Loss of interactivity t Talker echo t Listener echo All rights reserved © 2001, Alcatel

Rating as function of M 2 E delay for traditional G. 711 codec (no packet loss) Echo control bound (25 ms) Interactivity bound (150 ms) Maximum bound (400 ms) All rights reserved © 2001, Alcatel

Influence of echo control t Echo control can increase the echo loss value EL t Echo Controllers compliant with ITU-T Rec. G. 168 increase EL t t t by at least 30 d. B Even perfect echo control is possible (at the expense of some distortion) Electrical echo (introduced in 4 -to-2 -wire hybrid) has typically EL = 21 d. B Acoustic echo is dominant in non-optimized terminals and is harder to control than electrical echo Echo controller is simpler, if it is close to source of echo Echo control is required in an Vo. P transport environment All rights reserved © 2001, Alcatel

Rating for G. 711 codec (without PLC) Packet loss: 0%, 0. 5% and 1% All rights reserved © 2001, Alcatel

Rating for G. 729 codec with VAD Packet loss: 0%, 1%, 2%, 3% and 4% All rights reserved © 2001, Alcatel

M 2 E delay and packet loss bounds Bounds under perfect echo control t If there is no packet loss, the M 2 E delay can exceed 150 ms t If the M 2 E delay is below 150 ms some packet loss can be tolerated All rights reserved © 2001, Alcatel

Quality of a telephone conversation (using the E-model of ITU-T Rec. G. 107 and G. 109) (Very) Bad Perfect echo control Poor Medium High Best All rights reserved © 2001, Alcatel

Conclusions Quality of a telephone call t (Perfect) echo control is strongly recommended t Under perfect echo control the intrinsic quality remains constant if M 2 E delay < 150 ms t Choose codec to have an intrinsic quality that is good enough t e. g. G. 711, G. 729, . . . t Avoid transcoding from one low bit rate codec into another t Keep M 2 E delay and packet loss under control t bounds are codec-dependent t There is a trade-off between M 2 E delay and distortion

Conclusions Setting the parameters t The quality with which the voice flows are transported influence the overall quality, but … the choice of the codec, packet size and dejittering delay is also primordial t In the choice of the codec there is a trade-off between efficiency and quality t In the choice of the packet size there is a trade-off between efficiency and quality t Tuning the dejittering mechanism correctly is important to attain high quality

Addressability in Vo. IP Networks

Addressibility in Vo. IP t Question: How do you dial a Vo. IP user if all you have is their telephone number? alcatel. com ibm. com ge. com fcc. gov t Users resistant to change services if they have to change phone numbers All rights reserved © 2001, Alcatel

What is ENUM? t Telephone number mapping (RFC 2916, RFC 2915) t Allows a phone number to enable a caller to reach all kinds of devices (fax, IP telephone, email, etc. ) by knowing a single contact number t Originally proposed by Patrik Falstrom of Cisco t Uses DNS structure to map an E. 164 phone number into a series of Internet addresses: t SIP, H 323, SMTP, VPIM, IPP, etc. t Enables Local Number Portability, 800 services All rights reserved © 2001, Alcatel

How does ENUM work? DNS-A (9. 1. e 164. arpa) a = DN S-B p ar 4. ry e Qu 0 0. 0 5. . . 5 . . 8. 5 er sw = p si : n m co y. ox . 9 1. 9. ority Auth 16. e 1 l@ ie pr An Que ry 0. 5. 5 . 0. 5. 8 . 9. 1. e 164. arpa DNS-B (0. 5. 8. 9. 1. e 164. arpa) INVITE proxy. com INVITE “(919) 850 -5500" All rights reserved © 2001, Alcatel

What is TRIP? t Telephony Routing over IP t Identifies gateway for PSTN destinations t Being developed in IETF; currently only in IETF draft t Distributes routes to E. 164 prefixes (gateways) t Enables policy based routing t Based on BGP t Real-time recalculation of routes whenever paths becomes unavailable All rights reserved © 2001, Alcatel

How does TRIP work? LS-Z 1613, NHSx LS-Y 1613, NHSx 1613, NHSw LS-X LS-W NHSx 16132 -16135, GW-A 16136 -16139, GW-B All rights reserved © 2001, Alcatel

ENUM Implementation Issues t Should ENUM databases be public or commercial? t Public ENUM (Neu. Star) t Commercial ENUM: (Net. Number) t (Veri. Sign keeping its options open on both) t Which agency within the government will be responsible for ENUM implementation within the US t Selection of a Tier 1 ENUM operator for the United States portion of the North American Numbering Plan t State Dept Study Group A ENUM Ad Hoc t Formed to develop a recommendation to the USG on its participation in global and national ENUM implementation t Ad Hoc participants intend to form an industry forum to address the ENUM implementation in the United States All rights reserved © 2001, Alcatel

Regulatory Considerations

Context t The third ITU-T World Telecommunication Policy Forum (Geneva, March 7 -9 2001) discussed issues related to “Internet Protocol (IP) Telephony”. t The WTPF discussed the impact of IP telephony on regulation and policies of ITU member states and ways for offering technical assistance to developing countries. t A report of the secretary-general and draft opinions for the forum are finalized and available on the ITU website (http: //www. itu. int/wtpf). All rights reserved © 2001, Alcatel

What is at stake ? t Beyond the technological hype surrounding IP telephony, the real issue is the structure of the 21 st century world-wide telecom network and the nature - and mere existence ! - of the settlement system governing the interconnection between operators. t Many developing countries are fearing that widespread deployment of unregulated IP telephony traffic will dramatically lower the revenue stream drawn from the settlement system and, by way of consequence, the eventual insolvency of their local PTO(s). t The secretary-general’s report on IP telephony is quite objective and factual but the WTPF draft opinion recommendations reflect conflicting interests. All rights reserved © 2001, Alcatel

The “Netheads” view t Driven by CISCO, VON coalition, global operators (Worldcom, AT&T). t Objective: convince reluctant (mainly developing) countries to allow free competition of IP telephony with their local PTO. t Mantra: t IP is “the new” technology for telecommunications; t IP is much more efficient (cost) than legacy TDM; t IP networks open the way for new services and help reduce the “digital divide”; t IP telephony should not fall under the telecom regulation regime (or this regime should evolve) because it uses a new technology. All rights reserved © 2001, Alcatel

The EU view t Advocates the principle of technological neutrality. t EU has a strict definition of voice telephony in terms of the following four principles: t t it is offered commercially as such; it is provided to the public; it is provided to and from PSTN termination points; it involves speech transport and switching of voice in real-time with the same level of reliability and quality as existing PSTN networks. All rights reserved © 2001, Alcatel

Other Regulatory Implications t Regulatory parity (regulating services vs. technologies) t Should a telephone call be regulated differently if it is TDM, Vo. IP, FTTH, DOCSIS? t Protocol conversion t Is gateway functionality protocol conversion in a CI-II / CI-III context? t Unbundling t What are the UNE’s of a Vo. IP network? t How should competitive access provided in a Vo. DSL and FTTH environment? t CPE Deregulation t With gateway functionality moving to the end user All rights reserved © 2001, Alcatel

Further Reading … t David J Write, Voice over Packet Networks, J. Wiley, 2001. t Jonathan Davidson and James Peters, Voice over IP Fundamentals, Cisco Press, 2000. t Daniel Minoli and Emma Minoli, Delivering Voice of IP Networks, Wiley Computer Publishing, 1998. t David Collins, Carrier Grade Voice over IP, Mc. Graw-Hill, 2001. All rights reserved © 2001, Alcatel

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