VVooiiccee oovveerr IIPP TTuuttoorriiaall

AAaarrttii IIyyeennggaarr SSoolluuttiioonnss AArrcchhiitteecctt PPoollyyccoomm TTaabb llee ooff CC oonn tteenn ttss

•• IInnttrroodduuccttiioonn •• VVooIIPP NNeettwwoorrkk CCoommppoonneennttss//PPrroottooccoollss •• PPeerrffoorrmmaannccee PPaarraammeetteerrss •• RReegguullaattiioonnss •• SSeeccuurriittyy •• EEccoonnoommiiccss •• AApppplliiccaattiioonnss •• EEvvoolluuttiioonn SScceennaarriiooss IInn ttrroodd uuccttiioonn WW hh aatt iiss VVooIIPP??

• Legacy Telephony • TDM/SS7 based infrastructure • Traditional Class 5/Class 4 switches • Voice over IP • IP-based packet infrastructure for PSTN voice transport • New elements that collectively perform traditional functions and more • And what is IP Telephony? • Voice + Messaging + Video + Data over IP networks = IP Telephony • Public Internet : Best Effort Service • Managed IP Network : SLA based Service TThh ee PPaacckk eettiizzaattiioonn PPrroocceess ss

Analog Voice Filter Sample at 8000 Digital lower/higher samples per Quantization Encoding (400-4000kHz) frequencies second into bytes

Silence Suppression Compression (Optional). Echo Cancellation(if (Optional). Yields ~50% Yields further bandwidth reqd.) bandwidth gains gains UDP packet Digitized Voice Packet RTP packet encapsulated within IP encapsulated within encapsulated within packet RTP packet UDP packet

Voice Samples Voice Over IP Packet RTP Payload RTP Header

UDP Payload UDP Header

IP Payload IP Header TTrraadd iittiioonn aall PPSS TTNN NN eettww oorrkk

SS7 signaling SS7 network Call Control, Legacy Legacy Legacy Signaling, Class 4/5 Class 4/5 Class 4/5 Bearer/Media Switch Switch Switch and Features

TDM network

TDM bearer VVooIIPP NN eettww oorrkk SS7 signaling SS7 network Call Signaling Control IP signaling Soft IP Phones + Signaling Media IP bearer Gateway Gateway Controller IP Phones

Application IP network Media Server Server Media (conferencing) Media Media Features Gateway Gateway Bearer/ Media TDM TDM network bearer VVooIIPP NN eettww oorrkk CC oomm pp oonn eenn ttss TThh ee EE lleemm eenn ttss ....

• Terminals or Endpoints • IP Phones • Soft Phones/PC Phones • Media converter • Media Gateway/PSTN Gateway • Call Processor • Media Gateway Controller or Gatekeeper or Proxy Server or Softswitch • Signaling Gateway • Application Server • Media Server VVooIIPP NN eettww oorrkk PPaarraadd iigg mm ss Centralized Central Distributed Distributed Model Intelligence Intelligence Model Intelligent Master Intelligent Server Controller Server

Dumb Dumb Slave Slave GWs GWs Intelligent Client Intelligent Client Intelligent Intelligent Dumb Intelligent Server Slave Client Server Dumb Dumb GWs Slave Slave GWs GWs VVooIIPP PPrroottooccooll SS oouupp

H.323 MGCP SIP-T

SIP Megaco/H.248 BICC Call Control/Signaling Call Control/Signaling Gateway Control T RIP Softswitch-Softswitch

E N RTP P U SD M Bearer More ……. CC aallll CC oonn ttrrooll SS iigg nn aalliinn gg PPrroottooccoollss :: HH ..33 22 33

• ITU-T defined standard • Originally developed for ISDN based multimedia services over LAN • Distributed protocol model • Consists of • Terminals • Gatekeepers • Gateways • Multipoint control units • Umbrella protocol comprising of several other protocols like H.225, H.245, T.120 etc. defining RAS, capability negotiation etc. • Binary ASN.1 encoding • H.323v4 currently implemented everywhere • Future H.323v5 CC aallll CC oonn ttrrooll SS iigg nn aalliinn gg PPrroottooccoollss :: HH ..33 22 33

Gatekeeper

Gateway Gateway IP network

H.323 endpoint H.323 endpoint CC aallll CC oonn ttrrooll SS iigg nn aalliinn gg PPrroottooccoollss :: SS IIPP

•• IIEETTFF RRFFCC 33226655 ((oobbssoolleetteess RRFFCC 22554433)) •• DDeevveellooppeedd ffoorr mmuullttiimmeeddiiaa sseerrvviicceess oovveerr IIPP nneettwwoorrkkss bbaasseedd oonn hhttttpp mmooddeell •• DDeessiiggnneedd ttoo eemmppllooyy eexxiissttiinngg ppooppuullaarr IInntteerrnneett pprroottooccoollss lliikkee DDNNSS,, SSDDPP eettcc.. •• DDiissttrriibbuutteedd mmooddeell ccoonnssiissttiinngg ooff UUsseerr aaggeennttss aanndd SSeerrvveerrss •• TTeexxtt--bbaasseedd iimmpplleemmeennttaattiioonn iiss ppeerrcceeiivveedd ttoo bbee ssiimmpplleerr,, mmoodduullaarr,, eeaassiillyy aaddaappttaabbllee ttoo tthhee wwwwww CC aallll CC oonn ttrrooll SS iigg nn aalliinn gg PPrroottooccoollss :: SS IIPP

Redirect Location Server Registrar Server

IP network Proxy Proxy Server Server

SIP Phone SIP User Agent HH ..33 22 33 vveerrss uuss SS IIPP:: RR eeaalliittyy ??

• ITU protocols more tightly defined; IETF looks for looser working code • H.323 older and more established; SIP relatively newer but fast catching up • H.323 widely deployed today; SIP is being widely adopted by large players • Importance of the Internet and web-based applications increasing • SIP capable of giving service providers greater control of services, extensibility and interoperability with the www; hence, may eventually win the race • For a long time however, both these protocols need to co-exist • Robust standards must be developed to define interoperability to make things easier CC aallll CC oonn ttrrooll SS iigg nn aalliinn gg PPrroottooccoollss :: GG CC PP EE vvoolluuttiioonn

Source: Hughes Software Systems CC aallll CC oonn ttrrooll SS iigg nn aalliinn gg PPrroottooccoollss :: MM GG CC PP

• IETF informational RFC 3661 • Provides call control services in a packet network • Early implementation of Master/Slave protocol • Consists of media gateways and call agents • Call Agents-> centralized intelligent entities handling call control and signaling • Media Gateways-> dumb devices handling media • Call Agent communicates with Media Gateway via MGCP • Now a closed effort from standards perspective • MGCP implementations do exist today. MGCP variants NCS/TGCP are adopted by Packetcable. CC aallll CC oonn ttrrooll SS iigg nn aalliinn gg PPrroottooccoollss :: MM eegg aaccoo//HH ..22 44 88

• Enhances MGCP • Joint effort by ITU and IETF (IETF nomenclature- Megaco/RFC 3525, ITU nomenclature- H.248) • Provides call control services in a packet network • Adopts the Centralized model • Supports IP/ATM networks • MGC-MG communication via Megaco/H.248 • Deals with contexts and terminations • decouples physical terminations from logical (ephemeral) ones • more suited to handling multimedia • More complete and robust, standard allowing for multi- vendor interoperability CC oonn ttrroolllleerr -- CC oonn ttrroolllleerr PPrroottooccoollss :: SS IIPP--TT

• IETF RFC 3372 • Defines a framework to interface SIP with ISUP • To maintain feature transparency in the SIP network w.r.t PSTN to support IN services not supported in SIP • To deliver SS7 information (in its entirety ) to some trusted SIP elements • Integration methods • Encapsulation of ISUP within SIP using MIME • Translation of ISUP parameters to SIP header • Provision to transmit mid-call ISUP signaling messages through INFO method CC oonn ttrroolllleerr -- CC oonn ttrroolllleerr PPrroottooccoollss :: SS IIPP--TT

•• IImmpplleemmeenntteedd aatt SSIIPP--PPSSTTNN bboouunnddaarryy ggaatteewwaayyss • Carried end to end •• SSIIPP--TT iiss rreelleevvaanntt iinn tthhee ffoolllloowwiinngg sscceennaarriiooss • PSTN origination, IP termination • IP origination, PSTN termination • PSTN origination, PSTN termination with IP transit • IP origination, IP termination : SIP-T is not required CC oonn ttrroolllleerr -- CC oonn ttrroolllleerr PPrroottooccoollss :: BB IICC CC

• Development triggered by a need for a packet- based PSTN replacement • Functional separation of call and bearer signaling protocols in a broadband network • IP/ATM bearers in addition to TDM bearer • Uses SS7 signaling (with extensions to ISUP) • Binding information allows correlation between call control and bearer • BICC defines three capability sets • CS1: supports ATM-based (AAL1/AAL2) bearer • CS2: supports IP-based bearer • CS3: still in works to support advanced services and interoperability with SIP SS IIPP--TT vveerrss uuss BB IICC CC

SIP-T BICC • IETF defined • ITU defined • Defined to maintain feature • Defined to separate call transparency across SIP control from bearer (extends networks (deliver ISUP to ISUP to handle packet SIP endpoints) bearers) • Packet-based signaling and • SS7 signaling, Packet bearer bearer • Network is SS7 (ISUP) • SIP signaling signaled • IP bearer; ATM supported • TDM/ATM/IP bearers through RFC 3108 (may be some issues, but defined) • Intended for packet-based next-generation network • Provides a transition to pure supporting all existing advanced multimedia legacy services. services based SIP network BB eeaarreerr PPrroottooccooll:: RR TTPP

• IETF RFC 3550 (obsoletes RFC 1889) • End-to-end network transport services for multimedia applications • Services include payload type identification, sequence numbering, time stamping and delivery monitoring • Control protocol (RTCP) to monitor data delivery • Can be used with any transport protocol • Depends upon underlying transport layer for QoS • Applications typically use RTP over UDP PPuuttttiinn gg AA llll IInn gg rreedd iieenn ttss ooff tthh ee SS oouupp ttoogg eetthh eerr !! Protocol selection is a strategic decision depending on existing network and future services planned Ultimately, one winner will make it easy for all !

Media Application Server Media Server P I M Gateway S G C Controller P / H Signaling Media .2 4 8 Gateway Gateway S ) S SIP TP 7 Controller -T/BIC C C A/S 3U (M IP Network tran Sig P M (SS7) TC M G P/R e C PSTN T d P ia R ia / ed R H (TDM) M T .2 P 48 /R T C P Media TDM IP Phone (H.323/SIP) Gateway VVooIIPP NN eettww oorrkk PPeerrffoorrmm aann ccee TThh ee KK eeyy PPaarraamm eetteerrss

•• CCooddiinngg AAllggoorriitthhmmss •• EEcchhoo CCaanncceellllaattiioonn •• LLaatteennccyy •• JJiitttteerr//JJiitttteerr BBuuffffeerr •• PPaacckkeett lloossss •• TTrraannssccooddiinngg//TTaannddeemmiinngg •• QQooSS •• RReelliiaabbiilliittyy// AAvvaaiillaabbiilliittyy •• QQuuaalliittyy CC oodd iinn gg AA llgg oorriitthh mm ss

• Compression • What codec is used and their corresponding bit rates • Greater the compression, more the encoding delay • Determining appropriate packetization times and packet length • MOS score of codec determines perceived quality • VAD and CNG • At the transmitter • Detection of voice activity • Suppression of silence • At the receiver • Comfort Noise generation • Voice playback EE cchh oo CC aann cceellllaattiioonn

•• EEcchhoo ddeetteeccttiioonn aanndd ccaanncceellllaattiioonn •• AAvvaaiillaabbiilliittyy aanndd eecchhoo ssiiggnnaall rreettuurrnn lloossss qquuaalliittyy •• AAddjjuussttmmeennttss ttoo lloouuddnneessss rraattiinngg •• TTaaiill lleennggtthh iiss MMGG rroollee ddeeppeennddeenntt LL aatteenn ccyy //DD eellaayy

•• PPaacckkeettiizzaattiioonn DDeellaayy •• PPrrooppaaggaattiioonn DDeellaayy •• NNeettwwoorrkk PPrroocceessssiinngg DDeellaayy •• JJiitttteerr bbuuffffeerr ddeellaayy aanndd ssppeeeecchh ppllaayybbaacckk •• PPLLCCss aadddd aabboouutt 55mmss ddeellaayy •• PPSSTTNN bbeenncchhmmaarrkk ffoorr ttoollll qquuaalliittyy vvooiiccee iiss 115500mmss RRTTTT ((IITTUU GG..111144)) • Delay greater than 300ms is completely unacceptable for toll quality • An occasional packet loss is tolerable, but latency beyond 200 ms RT is not. JJ iitttteerr//JJ iitttteerr BB uuffffeerr

•• JJiitttteerr == DDeellaayy VVaarriiaattiioonn •• JJiitttteerr BBuuffffeerr ccoommppeennssaatteess ffoorr jjiitttteerr oonn tthhee rreecceeiivveerr ssiiddee •• JJiitttteerr bbuuffffeerr ssiizzee sshhoouulldd bbee ooppttiimmaallllyy cchhoosseenn • Rule of thumb: Jitter Buffer size = atleast 2 x speech frame size • Absolute jitter buffer size = end-to-end delay variation + some safety margin • Used by Gateways that have more processing power PPaacckk eett LL ooss ss

• Packet loss should be below 1% for acceptable quality • Use Codecs with packet loss concealment algorithms • E.g G.729, G.723.1 have built in PLC; add-on PLCs have to be used with G.711 and G.726 • PLC algorithms compensate about 40 ms of missing speech. • Delay >40ms & <200 ms, speech is clipped • Delay >200ms, speech dropouts • Packet loss is mostly bursty in nature. Hence, packet loss performance is directly related to packet size, the shorter the better TTrraann ss ccoodd iinn gg //TTaann dd eemm iinn gg

• Transcoding: Two or more encodings of a signal through different types of non-G.711 codecs separated by G.711 e.g G.726 to G.711 to G.729A • Tandeming: Two or more encodings of a signal through same types of non-G.711 codecs separated by G.711 e.g G.729A to G.711 to G.729A • Transcoding increases distortion and delay • Only one transcode can be tolerated before the network performance drops to unacceptable levels for most combinations of non-G711 codecs QQ uuaalliittyy ooff SS eerrvviiccee

•• MMeeaannss ttoo pprriioorriittiizzee vvooiiccee ppaacckkeettss •• RReeaall ttiimmee vvooiiccee ppaacckkeettss rreecceeiivvee hhiigghheerr pprriioorriittyy tthhaann nnoonn--rreeaall ttiimmee ddaattaa ppaacckkeettss •• HHeellppss iimmpprroovvee ppeerrffoorrmmaannccee bbyy ddeeccrreeaassiinngg ddeellaayy//jjiitttteerr ffoorr vvooiiccee ppaacckkeettss •• SSiiggnniiffiiccaanntt ddeellaayy//jjiitttteerr eevveennttss ccaann bbee aavvooiiddeedd oonnllyy bbyy iimmpplleemmeennttiinngg aa pprrooppeerr QQooSS SSttrraatteeggyy QQ ooSS SS ttrraatteegg yy • Best Effort • A class of service in which the network provides no guarantees to the edge equipment B est Effort • Prioritized Queuing Customer • Differentiation in the queuing Router of traffic for various classes of traffic • Assigns a priority or classification to every IP Customer Q oS aw are packet Router V oIP • Packets are sent in order of w ith Q ueuing N etw ork priority Edge • Traffic Engineered Tunnels Router • Constraint-based (traffic sensitive) connection-oriented Customer paths through a routed Router network W ith T raffic T unnels • MPLS Label Path • ATM VC SS pp eeeecchh QQ uuaalliittyy

Speech quality important for Factors that affect • Monitoring/fault-finding quality • Service level agreements » Background noise • Optimisation of network » Silence suppression Quality will remain an issue so » Low bit-rate coding long as bandwidth or » Errors (mobile, packet) processing power are limited » Delay • e.g. mobile, leased capacity » Echo » Handsets/access network •Quality measures: MOS; PSQM (Perceptual Speech Quality Measure); PAMS (perceptual analysis measurement system); PESQ (Perceptual Evaluation of Speech quality) •End-to-end speech quality is the key measure of voice QoS TThh ee BB iigg gg eess tt CC hh aalllleenn gg ee

T he V oIP N etw ork Cloud

The VoIP network must: -provide a customer’s service preferences anywhere - securely -adjusting to the constraints of the networks and access methods used: Wireline, Wireless, 3rd Party, Customer Owned, or Public Internet Clearly a list of codecs, packet sizes, loss rate and jitter targets are needed to ensure voice quality to a defined level of acceptability. VVooIIPP NN eettww oorrkk SS eeccuurriittyy NN eeww IIPP RR eeqq uuiirreemm eenn ttss

•• VViieewwiinngg ppaacckkeettss aass ppaarrtt ooff sseessssiioonnss •• PPoolliicciieess aarree rreeqquuiirreedd ffoorr SSeessssiioonnss •• NNeeww IIPP SSeerrvviicceess aarree eennaabblleedd ttoo hhaannddllee tthhiiss • Routing sessions between different networks, carriers and domains • Session packet flow anchoring • Detect failures and reroute • Usage based Billing/reporting at session flow level • Session aware borders for security SS eess ss iioonn aaww aarree ffiirreeww aallllss

• Two way VoIP communication impeded by NAT/NAPT • Signaling messages can be exchanged on defined port • Bearer messages are a problem • Special tags in SIP message to permit two way communication • Simple Traversal of UDP messages over NAT (STUN) • Creates NAT awareness in Clients • To modify SDP messages SS eess ss iioonn BB oorrdd eerr CC oonn ttrroolllleerr

•VoIP Firewall Traversal Solution for Carrier to Carrier Peering •Integrated SIP Application Layer Applicatio Softswitch Enterprise Gateway (ALG) n Service Session Session Provider Border Aware •Modify signaling traffic to Controller Firewall accommodate NAT/NAPT IP •Dynamic ‘pinhole’ opening/closing Backbone •Topology Hiding •Provide an address normalization Session boundary PSTN Border Gateway Controller •VoIP Media Anchoring Solution •VoIP Session QoS / Service Level PSTN IP Service Agreement Solution Provider •Per session based policing •Guaranteed service in congested environments •VoIP Session Admission Control Solution VVooIIPP RR eegg uullaattiioonn ss RR eegg uullaattiioonn ss

• Numbering Services • Rate Centre Association of Numbers • Impact on Number Conservation • Number Portability Compliance for VoIP providers? • Information service versus Telecommunications service • Access charges at Origination and Termination points? • CALEA • Requires North American telecommunications carriers to modify their equipment, facilities, and services to ensure that they are able to comply with authorized electronic surveillance. • Similar requirement for the VoIP? VVooIIPP NN eettww oorrkk EE ccoonn oomm iiccss IIss VVooIIPP eeccoonn oomm iiccaall??

•• WWhhaatt SSeerrvviiccee PPrroovviiddeerrss wwaanntt • Decrease expense • Lower capex on new infrastructure elements introduced • Lower opex on maintenance of existing infrastructure • Increase ARPU • Increase talk-time and use of Value added services (Centrex) • Ease of feature incorporation • Ease of Application development and innovation • Distributed architecture, fewer elements DD eepp llooyy mm eenn tt NN uumm bb eerrss ss uugg gg eess tt tthh ee ss aamm ee

• In 2003, IP accounted for the majority - 58% of network traffic - TIA • International VOIP calls grew from 0.2% of telephone traffic in 1998 to 10.4% in 2002 - Broadwatch News Analysis

• Total Internet protocol Major VoIP Providers (IP) revenues expected Vonage - 70,000 subscribers to grow in 2004 by 7.8 Free World Dial-up - 80,000 subscribers percent, achieving a total of $13.9 billion – Yahoo BB - Over 3 Million subscribers TIA FastWeb - 400K subscribers

3 VVooIIPP NN eettww oorrkk AA pp pp lliiccaattiioonn ss AA pp pp lliiccaattiioonn SS cceenn aarriiooss

•• IIPP PPBBXX •• IIPP CCeennttrreexx •• EEnnhhaanncceedd IIPP TTeelleepphhoonnyy •• CCllaassss 44 RReeppllaacceemmeenntt •• CCllaassss 55 RReeppllaacceemmeenntt •• AAnndd mmoorree…….... IIPP PPBB XX

• A CPE based IP telephony service that replaces a traditional TDM PBX

Customer Location Customer Location

Packet Computer Computer LA N LA N A T M Core A T M Frame Frame IP PBX Computer Computer IP PBX IP Phones IP Phones xD S L xD S L T 1 T 1 Ethernet Ethernet T D M T D M Class5 Class5 BB aass iicc IIPP CC eenn ttrreexx

• A network based IP telephony service that leverages a traditional Class 5 based Centrex service.

Customer Location

Customer Location Packet A T M Router Core Frame xD S L Computer Computer LA N A T M Router T 1 Frame Ethernet Computer Computer xD S L T 1 IP Phones LA N Ethernet

IP Phones IP Centrex G atew ay T D M

Class5

T raditional Centrex features delivered from here. EE nn hh aann cceedd IIPP TTeelleepp hh oonn yy

• A network based IP telephony service that provides multi-media voice over an IP network, in addition to basic Centrex features.

Customer Location

Customer Location Packet Router Core A T M Frame Computer Computer LA N xD S L Router A T M Frame T 1 Ethernet Computer Computer xD S L IP Phones T 1 LA N Ethernet M edia IP Phones A pplication G atew ay S erver PRI

A ll features delivered A ll off-net calls from here. Class5 CC llaass ss 44 RR eepp llaacceemm eenn tt •Scenario •ILECs, CLECs, IXCs, Large Corporations

•Benefits •By-pass traditional long distance toll network (Class 4) carriers and their per-minute usage rates and run their voice traffic over IP networks for a reduced cost.. •Lower costs with higher bandwidth efficiency

•Issues •Traffic engineering of IP network for PSTN QoS •Migration from Circuit to Packet-based Network CC llaass ss 44 RR eepp llaacceemm eenn tt

S S 7 N e tw o rk

End TA L I O ffic e S C TP End C la s s 5 S IP -T C la s s 4 O ffic e L o c a l C la s s 4 S o fts w itc h C la s s 5 S o fts w itc h (L EC ) L o c a l M G C P /H .2 4 8 P B X V o IP N e tw o rk

H ig h D e ns ity H ig h D e ns ity Tru nk ing M e dia Tru nk ing M e dia G a te w a y G a te w a y

S ig na ling B e a re r CC llaass ss 55 RR eepp llaacceemm eenn tt

Softswitch

PSTN Broadband Network IAD Telephone Media IP Network Gateway Scenario Out of Region and “Greenfield” deployments

Benefits Flexibility - Enable Rapid Deployment of New Services Distributed Architecture rather than Hierarchical Class Model

Issues Maturity of softswitch technology Ability to support all legacy systems supported by a Class 5 switch EE vvoolluuttiioonn ttoo VVooIIPP nn eettww oorrkk CC oonn ss eerrvvaattiivvee MM iigg rraattiioonn aann dd EE vvoolluuttiioonn

CLASS 5 DERIVED Broadband Network IAD Media Gateway Class 5 Switch

CLASS 5 + SOFTSWITCH Softswitch

Broadband Network IAD Media Gateway Class 5 Switch SOFTSWITCH ONLY

Softswitch

PSTN Broadband Network IAD Media IP Network Gateway VVooiiccee oovveerr BB rrooaadd bb aann dd NN eettww oorrkk AA rrcchh iitteeccttuurree

PSTN/SS7 SS7/PSTN Network Network

Softswitch Softswitch SIP

8 4 H 2 .2 . 4 H 8 d n a s

IP Network b s d e l e a r i o r W

Gateway B

Gateway e l r b e a v C

O L

S e D

Class 5 c TDM Network i o

Class 4 Class 4 V Gateway

PSTN/SS7 Network GR-303 Interface EE vvoolluuttiioonn ooff VVooIIPP -- GG eenn eerriicc VViieeww

C2P Packet Core Central Office

IP IP T D M Line Call Server Trunk CLA S S 5 GW GW H O S T TDM

TD Digital M Centrex M PSTN TD IP TD M IXC

AS Analog Centrex

T Multi Service D IP

M P I Edge Switch

Integrated Single IP Pipe Desktop IP (SIP Soft Client) F irew all for Voice,Data and Multi-Media

LD IP Network Campus Network IP Wireless Enhanced IP IP Device Telephony P A (SIP) W / Internet IP Mobile Network

PDA or Laptop Data PC Laptop