2G1325/2G5564 Practical Voice Over IP (VoIP): SIP and ......Maguire 2 of 22 [email protected] 2006.03.12 Practical Voice Over IP (VoIP): SIP and related protocols Module 1: Introduction.....

2G1325/2G5564 Practical Voice Over IP (VoIP):SIP and related protocols

Spring 2006, Period 4

Maguire Cover.fm Total pages: [email protected] 2006.03.12

© 2004, 2005, 2006 G.Q.Maguire Jr. .All rights reserved. No part of this course may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission of the author.

Last modified: 2006.03.12:13:16

KTH Information andCommunication Technology

Lecture notes of G. Q. Maguire Jr.

For use in conjunction with the two books:

• Luan Dang, Cullen Jennings, and David Kelly,Practical VoIP: Using VOCAL, O’Reilly, 2002, ISBN0-596-00078-2

• Henry Sinnreich and Alan B. Johnston, InternetCommunications Using SIP: Delivering VoIP andMultimedia Services with Session Initiation Protocol,Wiley, 2001, ISBN: 0-471-41399-2.

2 of 22Practical Voice Over IP (VoIP): SIP and related protocols

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[email protected] 2006.03.12

Module 1: Introduction.........................................Welcome to the course! ......................................Staff Associated with the Course.........................Instructor (Kursansvarig) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Administrative Assistant: recording of grades, registration, etc. - - - - - - - - - - - - - -

Goals, Scope and Method...................................Goals of the Course - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Scope and Method - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Prerequisites........................................................Contents ..............................................................Topics .................................................................Examination requirements ..................................Project .................................................................Assignment Registration and Report ..................Literature.............................................................Lecture Plan........................................................Voice over IP (VoIP) ............................................Potential Networks ..............................................Internetworking....................................................


................................... 38..................................... 39.................................... 40................................. 41................................. 42................................... 43.................................... 44................................... 45.................................... 46.................................... 47.................................. 48

- - - - - - - - - - - - - - - - - - - - - - - - - 48 - - - - - - - - - - - - - - - - - - - - - - - - 49- - - - - - - - - - - - - - - - - - - - - - - - - 49- - - - - - - - - - - - - - - - - - - - - - - - - 49 - - - - - - - - - - - - - - - - - - - - - - - - 50

................................... 51.................................... 54................................... 55


VoIP a major market............................................Handsets.............................................................VoIP Chipsets .....................................................Deregulation⇒ New operators ...........................Deregulation⇒ New Suppliers...........................Let them fail fast!.................................................Latency ...............................................................VOIP Modes of Operation...................................IP based data+voice infrastructure .....................Voice Gateway....................................................Voice over IP (VOIP) Gateways ..........................Voice representation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Signaling - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Fax Support - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Management - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Compatibility - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Cisco’s Voice Over IP .........................................Intranet Telephone System .................................Wireless LANs.....................................................


................................... 56................................... 57.................................. 58.................................... 59.................................. 60..................................... 61................................. 63.................................. 64................................. 65- - - - - - - - - - - - - - - - - - - - - - - - - 65 - - - - - - - - - - - - - - - - - - - - - - - - 65

................................... 66

.................................... 67................................... 68.................................... 70g................................. 71..................................... 72................................... 73


Telia’s HomeRun.................................................Ericsson’s "GSM on the Net" ..............................VOIP vs. traditional telephony .............................Economics ..........................................................VoIP vs. traditional telephony ..............................Patents................................................................Deregulation⇒ Trends .......................................Carriers offering VOIP .........................................MCI (formerly WorldCom) Connection................Previously - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Today - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Level 3 Communications Inc...............................TeliaSonera Bredbandstelefoni...........................Emulating the PSTN............................................Calling and Called Features................................Beyond the PSTN: Presence & Instant MessaginPresence-Enabled Services ................................Three major alternatives for VoIP .......................


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................................... 77.................................... 78................................... 79..................................... 80.................................... 84................................... 85................................... 86.................................... 87................................... 88.................................... 89................................... 90.................................... 91.................................. 92................................... 93


Negatives ............................................................Deregulation⇒ New Regulations.......................Regulations in Sweden .......................................Programmable “phone” .......................................Conferences ........................................................Not with out problems .........................................References and Further Reading........................Acknowledgements.............................................Module 2: VoIP details........................................Traditional Telecom vs. Datacom........................VoIP details: Protocols and Packets ...................RTP and H.323 for IP Telephony .......................RTP, RTCP, and RTSP.......................................Real-Time Delivery .............................................Packet delay........................................................Dealing with Delay jitter ......................................Delay and delay variance (jitter)..........................


.................................... 94

.................................... 95.................................... 96.................................... 97.................................... 98................................. 99................................. 100.................................. 101................................. 103.................................. 105................................. 106................................ 107.................................. 108.................................. 109.................................. 112................................ 113................................ 114


Playout delay ......................................................When to play.......................................................Retransmission, Loss, and Recovery ..................Patterns of Loss ..................................................Loss concealment................................................VoIP need not be “toll quality” .............................RTP: Real-Time Transport Protocol....................Payload types......................................................Audio Encodings .................................................Timestamps.........................................................Stream translation and mixing.............................RTP Control Protocol (RTCP) ...........................Compound Reports .............................................Proposed RTCP Reporting Extensions...............RTP translators/mixers .......................................Synchronizing Multiple Streams ..........................RTP Transport and Many-to-many Transmission


exing ........................ 115................................. 116................................. 117.................................. 118................................... 119- - - - - - - - - - - - - - - - - - - - - - - - - 121- - - - - - - - - - - - - - - - - - - - - - - - - 124

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- - - - - - - - - - - - - - - - - - - - - - - - 129

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.................................. 131.................................. 132.................................. 133................................... 134 - - - - - - - - - - - - - - - - - - - - - - - - - - - 134

................................ 135


Sessions, Streams, Protocol Port, and DemultiplFurther details of RTP and RTCP........................Real Time Streaming Protocol (RTSP) ...............RTSP session description ...................................References and Further Reading........................RTP and RTCP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - RTSP- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 3: SIP......................................................Session Initiation Protocol (SIP) .........................SIP WG’s deliverables.........................................Related working groups.......................................Historic - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Session Initiation Protocol (SIP) .........................Is SIP simple? .....................................................SIP, RTP, and RTSP...........................................SIP actors ............................................................SIP Methods and Status Codes..........................SIP Status codes - patterned on and simular to HTTP’s status codes: - - - - - - - - - -

SIP Uniform Resource Indicators (URIs).............


................................... 136

.................................. 137................................. 138................................. 139............................... 140................................. 141................................ 142.................................. 143............................... 144.................................. 145.................................. 146.................................. 147................................. 148.................................. 149................................... 150.................................. 151.................................. 152


Issues to be considered ......................................Address Resolution.............................................SIP timeline .........................................................SIP Invite .............................................................Bob’s response to Alice’s INVITE........................ACK.....................................................................SIP Invite (method/URI/version)..........................SIP Via................................................................Dialog (Call leg) Information ................................SIP CSeq.............................................................SIP Contact .........................................................SIP Content Type and Length ............................SIP Max-Forwards...............................................Other header fields..............................................Several types of SIP Servers..............................SIP Trapezoid ....................................................SIP Call Setup.....................................................


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................................. 154

................................... 155.................................. 156.................................. 157.................................. 158................................ 159................................. 160................................. 161................................ 162

.................................. 164................................. 165................................. 166................................... 167................................... 168


SIP Call Setup Attempt........................................SIP Call Setup Attempt........................................SIP Presence ......................................................SIP B not Present ................................................SIP Registration Example...................................Purpose of registration........................................REGISTERing ......................................................SIP Call Setup Attempt........................................SIP Session Termination using BYE...................SIP Session Termination using CANCEL............CANCEL andOPTIONS ............................ 163CANCEL - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 163OPTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 163

Unsuccessful final responses are hop-by-hop.....Authentication .....................................................SIP Method Extensions in other RFCs ................SIP Extensions and Features..............................SIP Presence - Signed In....................................


.................................. 170................................. 171................................... 172................................ 173................................. 174

.................................. 176................................... 178.................................. 179.................................. 180.................................. 181................................ 182.................................. 183................................. 184................................... 185................................. 191


SUBSCRIBE andNOTIFY .......................... 169SIP Instant Messaging Example .........................SIP Instant Messaging Example (continued).......Message example...............................................Midcall signalling .................................................Call Control .........................................................Example of usingREFER ........................... 175QoS and Call Setup.............................................SIP Message retransmission ..............................RFC 3261 - Routing Changes.............................RFC 3261 - New Services ..................................Compression of SIP ............................................Intelligent Network service using SIP ..................Capability Set 1: Services...................................Capability Set 2 ...................................................Features..............................................................SIP development, evolution, …...........................


.................................. 192

................................. 193................................... 194 - - - - - - - - - - - - - - - - - - - - - - - - 194 - - - - - - - - - - - - - - - - - - - - - - - - - 198

) ............................... 200.................................. 201................................... 202 - - - - - - - - - - - - - - - - - - - - - - - - 202

................................. 203................................. 204................................. 205 - - - - - - - - - - - - - - - - - - - - - - - - - 205

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.................................. 209................................... 210................................. 211................................. 212


Gateways.............................................................Significance .........................................................References and Further Reading........................SIP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -ITU Services CS-1 and CS-2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 4: Session Annoucement Protocol (SAPSession Announcement Protocol (SAP) .............References and Further Reading........................SAP- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 5: Session Description Protocol (SDP) ..Session Description Protocol (SDP)....................Session Description Protocol (SDP)....................Internet drafts related to SDP: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

SDP Message Details..........................................Session description .............................................SDP Offer/Response Example............................SDP Response Example ....................................Session Modification ...........................................Session modification (continued) ........................


.................................. 213ion Protocol (SDP)[70] 214................................. 215................................. 216.................................. 217................................ 218................................... 219- - - - - - - - - - - - - - - - - - - - - - - - - 219

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................................. 224................................. 225.................................. 228.............................. 229ber........................... 230................................. 231................................ 232


Start and Stop Times...........................................Grouping of Media Lines in the Session DescriptLip Synchronization ............................................Next generation of SDP (SDPng) ........................SDPng structure..................................................Why XML?...........................................................References and Further Reading........................SDP- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 6: DNS and ENUM .................................Telephony URL and Phone-Context ...................SIP URL ..............................................................ENUM .................................................................DNS ....................................................................NAPTR - Naming Authority Pointer [77] ..............To find the DNS names for a specific E.164 numENUM Services...................................................EUNM Timeline ...................................................


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................................. 236................................... 237 - - - - - - - - - - - - - - - - - - - - - - - - 237 - - - - - - - - - - - - - - - - - - - - - - - - 237

................................ 242................................ 243................................ 244................................... 245 - - - - - - - - - - - - - - - - - - - - - - - - 245 - - - - - - - - - - - - - - - - - - - - - - - - 245

................................. 246

.................................. 247.................................. 248.................................. 249................................. 250.................................. 251................................. 252


Sweden’s ENUM Mapping...................................VISIONng Association.........................................SIP goes beyond ENUM......................................References and Further Reading........................DNS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -ENUM- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 7: SIP Mobility ........................................SIP Mobility .........................................................Local Number Portability .....................................References and Further Reading........................SIP Mobility - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Service Mobility - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 8: SIP Service Creation ..........................SIP Service Creation...........................................Services implemented by x.................................Services implemented by Extensions .................SIP Service Logic ...............................................Call Processing Language (CPL)........................SIP Common Gateway Interface (CGI)...............


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................................. 254gy - SIP and Jain ..... 257.................................. 258................................. 259................................. 260™).......................... 261................................... 262 - - - - - - - - - - - - - - - - - - - - - - - - - 262 - - - - - - - - - - - - - - - - - - - - - - - - 263- - - - - - - - - - - - - - - - - - - - - - - - - 263- - - - - - - - - - - - - - - - - - - - - - - - - 263 - - - - - - - - - - - - - - - - - - - - - - - - 263- - - - - - - - - - - - - - - - - - - - - - - - 264

.................................. 265................................... 266................................... 267................................... 268.................................. 269


SIP Java Servlets ...............................................JAIN APIs............................................................US National Institute of Standards and TechnoloParlay ..................................................................SIP Request-URIs for Service Control ................Reason Header ..................................................Voice eXtensible Markup Language (VoiceXMLReferences and Further Reading........................SIP Service Creation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -JAIN - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Parley - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - SIP Request URI - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Reason Header - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -VoiceXML - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 9: User Preferences................................User Preferences ................................................Contact parameters ............................................Contact header example.....................................Accept/Reject-Contact header(s) ........................


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................................. 271.................................. 272.................................. 273.................................. 274................................... 275 - - - - - - - - - - - - - - - - - - - - - - - - - 275

................................ 277

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................................. 279................................ 280................................. 281 - - - - - - - - - - - - - - - - - - - - - - - - - 287

TESLA) .................. 289................................. 290................................. 292................................. 293................................. 294


Callee (i.e., called party) Parameter processing .Accept-Contact Example.....................................Request-Disposition............................................SIP Service Examples.........................................Privacy-Conscious Personalization ....................References and Further Reading........................User Preferences - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 10: SIP Security, NATs, and Firewalls ...SIP Security ........................................................SIP Digest Authentication ...................................SIPand S/MIME ..................................................SDP & RTP security............................................Secure Call Setup [126] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Efficient Stream Loss-tolerant Authentication (NATs and Firewalls.............................................Types of NAT......................................................Cone vs. Symmetric NAT ...................................NAT traversal methods........................................


Network Address Translation))

.................................. 297................................. 298................................. 299ll Traversal ........... 300.............................. 301................................ 302ASN.1) ................... 303................................ 305................................. 306............................... 307................................ 308............................... 309.................................. 310................................ 311................................. 312


STUN (Simple Traversal of UDP through NATs (296STUN steps.........................................................UDP and TCP Firewall Traversal problems........UDP and TCP NAT Traversal problems.............SIP Application Level Gateway (ALG) for FirewaMiddlebox communications (MIDCOM) ..............Application aware Middlebox ..............................Security flaws in Abstract Syntax Notation One (Swedish Electronic Communications Act ............Recording of Call Contents .................................Privacy & Lawful Intercept (LI)...........................Reasonably Available Information.......................EU privacy and Lawful Intercept (LI) ...................Intercept architecture ..........................................Voice over IP Security Alliance ...........................Spam over Internet Telephony (SPIT).................


................................... 313- - - - - - - - - - - - - - - - - - - - - - - - - 313- - - - - - - - - - - - - - - - - - - - - - - - - 314- - - - - - - - - - - - - - - - - - - - - - - - - 316 - - - - - - - - - - - - - - - - - - - - - - - - 319

................................. 323.................................. 324................................ 325................................. 326.................................. 327................................. 32875]........................... 329.................................. 331................................ 332.................................. 333................................. 334EOPRIV)................ 335................................... 336 - - - - - - - - - - - - - - - - - - - - - - - - - 336


References and Further Reading........................SIP Security - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - RTP encryption - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - NATs and Firewalls - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Privacy - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 11: SIP Telephony..................................SIP Telephony ....................................................Telephony Routing over IP (TRIP) ......................Call Control Services...........................................Call Center Redesign using SIP..........................Additional SIP Telephony services .....................Emergency Telecommunication Service (ETS)[1Emergency Services (E911) ...............................Public Safety Answering Point (PSAP)................Vonage 911 service.............................................Vonage equips PSAps with VoIP........................Geographic Location/Privacy Working Group (GReferences and Further Reading........................Emergency services - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


- - - - - - - - - - - - - - - - - - - - - - - - - 337 - - - - - - - - - - - - - - - - - - - - - - - - 337

................................. 339

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.................................. 342.................................. 343................................... 344- - - - - - - - - - - - - - - - - - - - - - - - - 344- - - - - - - - - - - - - - - - - - - - - - - - - - 345 - - - - - - - - - - - - - - - - - - - - - - - - 345- - - - - - - - - - - - - - - - - - - - - - - - - - 345

................................ 347

................................. 348

................................ 349et Servers (SPIRITS) 350................................ 351................................... 352 - - - - - - - - - - - - - - - - - - - - - - - - 352 - - - - - - - - - - - - - - - - - - - - - - - - 352 - - - - - - - - - - - - - - - - - - - - - - - - 354


SIP Telephony - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - TRIP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 12: SIP Conferencing .............................Conferencing.......................................................Conferencing Models [176].................................SIP Conferencing................................................Speaker recognition in a conference...................References and Further Reading........................SIP Conferencing - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Session Annoucement Protocol - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - SMIL- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Speaker recognition in a conference - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 13: Mixed Internet-PSTN Services .........Mixed Internet-PSTN Services............................PSTN and Internetworking (PINT) ......................Servers in the PSTN Initiating Requests to InternTelephony Routing over IP (TRIP) ......................References and Further Reading........................PINT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -SPIRITS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -TRIP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


- - - - - - - - - - - - - - - - - - - - - - - - 354

................................ 355............................. 356................................. 357.................................. 358................................. 359................................... 360................................ 361................................. 362................................ 364................................... 365- - - - - - - - - - - - - - - - - - - - - - - - - 365- - - - - - - - - - - - - - - - - - - - - - - - - 365

.................................. 366................................ 367.................................. 368................................. 369.................................. 370


ISUP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 14: AAA and QoS for SIP.......................Authentication, Authorization, Accounting (AAA)SIP Accounting....................................................Open Settlement Protocol (OSP)........................Achieving QoS ....................................................Some measured delays.......................................Underlying Quality ...............................................Voice Quality.......................................................Rating voice quality in practice ............................QoS Proprietary vs. Standards based.................Past - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2002 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

QoS for SIP.........................................................VoIP traffic and Congestion Control....................Delay and Packet Loss effects ............................When to continue (try again) ...............................More about congestion .......................................


................................ 371

................................ 372

................................... 373................................ 379 (SIPPING) ............. 380................................. 382.................................. 383............................... 384- - - - - - - - - - - - - - - - - - - - - - - - - 385 - - - - - - - - - - - - - - - - - - - - - - - - - 386

ponse (IVR) ............ 387.................................. 388.................................. 389................................... 390 - - - - - - - - - - - - - - - - - - - - - - - - 390

................................ 391

.................................. 392................................. 393


VoIP quality over IEEE 802.11b..........................Application Policy Server (APS)..........................References and Further Reading........................Module 15: SIP Applications ...............................Session Initiation Protocol Project INvestiGationApplication Service Components ........................Advantages .........................................................Collecting DTMF digits for use within a service ..Reponse “3. 200 OK” looks like: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Controller issues a “re-Invite” at 11 which looks like: - - - - - - - - - - - - - - - - - - - - - -

Voice Portal Service using Interactive Voice ResManaging Services..............................................Lots more services ..............................................References and Further Reading........................SIPPING - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 16: More than Voice................................Non-voice Services and IP Phones.....................XML ....................................................................


................................. 394.................................. 395................................. 396................................. 397.................................. 398................................ 399.................................. 400................................ 402.................................. 405- - - - - - - - - - - - - - - - - - - - - - - - - 405 - - - - - - - - - - - - - - - - - - - - - - - - 405

................................... 406 - - - - - - - - - - - - - - - - - - - - - - - - - 406- - - - - - - - - - - - - - - - - - - - - - - - - 406

................................ 409

................................ 410

................................. 411................................ 412................................. 413


Invoking RTP streams .........................................More details ........................................................Services for sale - building a market ...................Network Appliances ............................................Proposed Extension of SIP .................................Service Location Protocol (SLP) URL.................Example service..................................................Example of service portability..............................Text .....................................................................Interleaved text - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Timed Text- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

References and Further Reading........................Phone Services - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Network Appliances- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Module 17: VOCAL.............................................VOCAL System Overview...................................VOCAL Servers...................................................Scaling of a VOCAL system ................................For comparison with a PBX ................................


................................. 414.................................. 415................................... 416................................. 417................................... 418are............................ 419.................................. 420.................................. 421.................................. 422.................................. 423.................................. 424................................... 426................................. 427.................................. 428................................... 429


Marshal server (MS)............................................Redirect Server (RS)...........................................Feature Server (FS)............................................Residential Gateway (RG)...................................References and Further Reading........................Module 18: SIP Express Router and other SoftwSIP Express Router (SER)..................................SipFoundry .........................................................Other SIP Proxies ...............................................SIP Tools ............................................................SIP Clients ..........................................................References and Further Reading........................Module 19: Non-SIP applications .......................Skype ..................................................................References and Further Reading........................

2G132 oice Over IP (VoIP):rotocolsriod 4

Maguire Total pages: [email protected]

© 2004, 2005, 2006 G.Q.Maguire Jr. .All rights reserved. No part of this course hotocopying, recording, or otherwise, without written permission of the author.

Last modified: 2006.03.12:16:45

KTH Information andCommunication Technology

Introductionof G. Q. Maguire Jr.

the two books:

nings, and David Kelly,OCAL, O’Reilly, 2002, ISBN

an B. Johnston, Internet SIP: Delivering VoIP andth Session Initiation Protocol,71-41399-2.

5/2G5564 Practical VSIP and related p

Spring 2006, Pe

Introduction.fm 2006.03.12

may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, p

Module 1:Lecture notes

For use in conjunction with

• Luan Dang, Cullen JenPractical VoIP: Using V0-596-00078-2

• Henry Sinnreich and AlCommunications UsingMultimedia Services wiWiley, 2001, ISBN: 0-4

Module 1: 24 of 84Practical Voice Over IP (VoIP): SIP and related protocols

se!

s on SIP and related protocols,ls which are used.

e course web page

ation of KTH to:

Maguire Welcome to the [email protected] 2006.03.12

Welcome to the courThe course should befun.

We will dig deeper into Voice over IP - with a focubut may also examine some of the other protoco

Information about the course is available from thhttp://www.imit.kth.se/courses/2G1325/

Note that the above URL will change - due to the reoganiz

http://www.cos.ict.kth.se/education/msc/ccs/courses/2G1325/

http://www.imit.kth.se/courses/2G1325/http://www.cos.ict.kth.se/education/msc/ccs/courses/2G1325/


Course

se>

Maguire Staff Associated with the [email protected] 2006.03.12

Staff Associated with the Instructor (Kursansvarig)

prof. Gerald Q. Maguire Jr.

Administrative Assistant: recording of grades, registration, etc.

Irina Radulescu


thod

ms are, their basic

re.development in this area.

mmunication Application

nd examine some places where it can explore).

g a written report andject.

Maguire Goals, Scope and [email protected] 2006.03.12

Goals, Scope and MeGoals of the Course

• To understand what Voice over IP (VoIP) systearchitectures, and the underlying protocols

• To be able to read and understand the literatu• To provide a basis for your own research and Scope and Method

• We are going to examine the Vovida Open CoLibrary (VOCAL ) system1• to understand both the details of the system(s) and• to abstract from these details some architectural features a

can be extended (thus using it as a platform on which you

• You will demonstrate your knowledge by writingiving an oral presentation describing your pro

1. The source code is available fromvovida.org

vovida.org


ations (this requires

Maguire [email protected] 2006.03.12

Prerequisites• Internetwork (2G1305) or• Equivalent knowledge in Computer Communic

permission of the instructor)


(VoIP) systems are, their basicwill primarily focus on theocols.

a project of ~50 hours effort.


ContentsThe focus of the course is on what Voice over IParchitectures, and the underlying protocols. We Session Initiation Protocol (SIP) and related prot

The course consists of 10 hours of lectures and


erver, Registrar Server,


Topics• Session Initiation Protocol (SIP)• Real-time Transport Protocol (RTP)• Real-time Streaming Protocol (RTSP)• Common Open Policy Server (COPS)• SIP User Agents• Location Server, Redirect Server, SIP Proxy S

... , Provisioning Server, Feature Server• Call Processing Language (CPL)


ents

Maguire Examination [email protected] 2006.03.12

Examination requirem• Written and Oral project reports

Grades: U, 3, 4, 5


and to show that you haveourage you to find a topic which

y understand the material)

med by yourself). Each oral reports.ctor before starting.


ProjectGoals: to gain analytical or practical experience mastered some knowledge in this area and to encinterests you (since this will motivate you to reall

• Can be done in a group of 1 to 3 students (forstudent must contribute to the final written and

• Discuss your ideas about topics with the instru


d Report.se>, subject=2G1325 topic

00 words) for each student.ach paper suitable for submission

(in the case where the report is ap can be explained in the overall

; 2) who did what; if you haved describe the methods and toolsur analysis.

resentations scheduled

.se>

the deadlines!

Maguire Assignment Registration and [email protected] 2006.03.12

Assignment Registration an• Registration: 3 April 2006, to


s:

Practical VoIP: Using

t Communications Using with Session Initiation

s necessary. A list of interestingand in the references and further

rature in conjunction with youre your sourcesin your report.


LiteratureThe course will mainly be based on the two book

• Luan Dang, Cullen Jennings, and David Kelly,VOCAL, O’Reilly, 2002, ISBN 0-596-00078-2.

• Henry Sinnreich and Alan B. Johnston, InterneSIP: Delivering VoIP and Multimedia ServicesProtocol, Wiley, 2001, ISBN: 0-471-41399-2

We will refer to other books, articles, and RFCs aliterature will be available on the course web pagereading section of each lecture module.

In addition, you will be searching & reading the liteprojects. Please make sure that youproperly referenc


Maguire Lecture [email protected] 2006.03.12

Lecture Plan• Introduction

• Course arrangement• Set the context of VoIP, both technically and economically

• VoIP details• Session Initiation Protocol (SIP)• Session Description Protocol (SDP)• DNS and ENUM

• Mobility• Service Creation• User preferences• Security, NATs, and Firewalls• SIP Telephony• Conferencing• Mixed Internet - PSTN services• AAA and QoS• More than just voice!


)srocessingin theend points.

etwork - where processing is

(Now) we think about aconverged network whichis aglobal network

k

t

terminal

Maguire Voice over IP (VoIP)[email protected] 2006.03.12

Voice over IP (VoIPVoIP is an End-to-End Architecture which exploitp

Unlike the traditional Public Switch Telephony Ndoneinside the network.

Network Convergence:In the past, many different networks -each optimized for aspecific use: POTS, data networks (such as X.25), broadcastradio and television, … and each of these in turn often hadspecific national, regional, or proprietary implementations)

⇒

CODEC

IP stack

radio

CODEC

IP stac

etherne

Cellular IP terminal Fixed IP

VoIP server

call/sessionroutingtranscoding

IP cloud

IP end-to-end


s

f the underlying network,

Ring

MH

Ad hoc

AN

UPSTN

Maguire Potential [email protected] 2006.03.12

Potential Network

• We will focus on VoIP, largely independently oi.e., LAN, Cellular, WLAN, PAN, Ad hoc, … .

Figure 1: Internet and PSTN

WANswitch

switch switch

switchR

R

R

R

R

R

FDDI

Token H

H

MSCHLR/VLR

BSCBTS

IWU

Cellular networks

WLAN

P

Ethernet LANs

AP

… …

…

…

IW

MH

MH

MH

MH


of multiple networksechnologies by providing and makes them

aed sampling rate, typicallyvoice coding; however, VoIP isr or lower data rates bandwidth between the end

fers is quality which is:

still acceptable)

systems.


InternetworkingInternetworking is

• based on the interconnection (concatenation)• accommodates multiple underlying hardware t

a way to interconnect heterogeneous networksinter-operate.

Public Switched Telephony System (PSTN) usesfix8kHz and coding to 8 bits, this results in 64 kbpsnot limited to using this coding and could havehighedepending on the CODEC(s) used, the availablepoints, and the user’s preference(s).

One of the interesting possibilities which VoIP of

• better that “toll grade” telephony or• worse than “toll grade” telephony (but perhaps

This is unlike thefixed quality of traditional phone


etwhich began with H.323 and hasrs of users and a large variety ofincreasing numbers of vendors,arket?

tions around 1997, buts that it took more thans, but the next 1 million

er Cisco losing momentum?”,tember 17, 2003, 4:00 AM PT

5), they had shipped theiran one year earlier.)

Maguire VoIP a major [email protected] 2006.03.12

VoIP a major markVoice over IP has developed as a major market -now moved to SIP. There are increasing numbeVoIP hardware and software on the market. Withthe competition is heating up - is it a maturing m

“Cisco began selling its VoIP gear to corporauntil the past year, sales were slow. Cisco notethree years to sell its first 1 million VoIP phonetook only 12 months.”

Ben Charny , “Is VoIP pioneCNET News.com, Sep

As of their fiscal year 2005 (ending July 30, 2006 millionth IP phone[9]. (This is 3 million more th


ets:

.clarisys.com/ ,k, IPEVO, …

® Data Phone.com/rverndset and their server, but I this mis-feature.

nd e805) with VoIP and.

ml

d GSM & 802.11 ("GSM.11"),


HandsetsThere are now lots of USB attached VoIP hands

• http://www.clarisys.com/ Claritel-i750 http://wwwPlantronics DA60, Net2Phone, Linksys, D-Lin

WLAN Handsets:

• starting with Symbol Technologies’s NetVision• Vocera Communications Badge http://www.vocera

• runs speech recognition software in a network attached se• unfortunately it uses a proprietary protocol between the ha

expect others will make similar devices which will not have

• Toshiba announced two PDAs (models e800 aWi-Fi; as have NTT’s DoCoMo and Sony Corp

• for more http://www.sipcenter.com/vsts/vsts_sipphones.ht

VoIP cellular handsets, e.g. TTPCom’s combineNokia, Qtek, …

http://www.vocera.com/http://www.sipcenter.com/vsts/vsts_sipphones.htmlhttp://www.clarisys.com/


issinesstelephonehandsetsutions.html

, IrDA, SPI, 16 programmable I/O, …lumn inputs/outputs to control up …

or core running at 80 MIPS compression/decompression

og-to-digital converters (A/D),t and output)

nable high quality

Maguire VoIP [email protected] 2006.03.12

VoIP ChipsetsAgere Systems’ VoIP Phone-On-A-Chip - targetbuandspeakerphoneshttp://www.agere.com/mobility/voip_sol

Two ICs:

• T8302 IPT_ARM (Advanced RISC Machine)• Up to 57.6 MHz general-purpose processor• controls the system I/O: two 10/100Base-T Ethernets, USB

pins (some could be used to interface to an LCD module)• general telephone control features: 7 row outputs and 8 co

to 56 LEDs and scan up to 56 keys, 6 different flash rates,

• T8301 IPT_DSP (digital signal processor)• Based on Agere Systems DSP1627 digital signal process• single-cycle multiply accumulate instruction supports voice

and echo cancellation algorithms• Includes two 16-bit digital-to-analog (D/A), one 16-bit anal

low-pass filters, audio amplifier, lots of buffers (for for inpu

A special feature isacoustic echo cancellation to espeakerphone. See also [3].

http://www.agere.com/mobility/voip_solutions.html


erators

ch technology

loads as of 2005.02.10)

7,596,653 as of 2005.02.10

rss.xml updated

Maguire Deregulation ⇒ New [email protected] 2006.03.12

Deregulation ⇒ New opLots of new actors appeared as operators:

• MCI (formerly Worldcom) - http://www.mci.com/• Qwest - http://www.qwest.com/• Level3 http://www.level3.net/

• (3)Voice, an IP based long distance service using Softswit

• Vonage - http://www.vonage.com /• 1.5 million lines in service• > 42 million as of March 1, 2006 [12]

• Skype™ Technologies http://www.skype.com/• “Skype is free Internet telephony that just works.”• 200 million downloads as of 2005.11.08 (67,430,762 down

– ~1 Million downloads/day– downloads at peak are ~0.5 Gbit/sec

• 19,627,534,145 minutes served as of 2006.03.12 vs. 4,70• > 5 million simultaneous users on Jan. 23 2006 [13]• statistics as an RSS feed at: http://share.skype.com/stats_

every few minutes

• …

http://www.skype.com/http://www.vonage.comhttp://www.level3.net/http://www.qwest.com/http://www.mci.com/http://share.skype.com/stats_rss.xml


uppliers

atacom vendors.

vendors.

o opertors) were reorganizing,to the Telecom meltdown!

ucts/sip/

Maguire Deregulation ⇒ New [email protected] 2006.03.12

Deregulation ⇒ New SLots of new actors as equipment suppliers:

• Cisco , 3Com, Nortel Networks, …

Traditional telecom equipment vendors buying d

Lots of mergers and acquisitions among datacom

As of Fall 2002, many of these vendors (similar tselling off divisions, reducing staffing, … -- due However, some have survived (or been reborn).

For a list of SIP products see:http://www.pulver.com/prod

http://www.pulver.com/products/sip/


lecom troubles is thatas subsumed (and will

embodied in otherausing the immediateircuit-based telephony

atson, Robert J. Berger, et al.,hael Powell, October 21, 2002press/powell.html

which recommends that the FCC:ts. The policy should be one of

t, while not yet extinct, is artificially prolong its use.

to thwart municipal,on’t fit the telephone company

d aggressively expand unlicensed

Maguire Let them fail [email protected] 2006.03.12

Let them fail fast!We hold that the primary cause of current teInternet-based end-to-end data networking hsubsume) the value that was formerlycommunications networks. This, in turn, is cobsolescence of the vertically integrated, cindustry of 127 years vintage.

Izumi Aizu, Jay BLetter to FCC Chairman Mic

http://pulver.com/

The extent of this transformation is well described in their complete letter• ‘‘Resist at all costs the telephone industry’s calls for bailou

"fast failure."• Acknowledge that non-Internet communications equipmen

economically obsolete and forbear from actions that would• Discourage attempts by incumbent telephone companies

publicly-owned and other communications initiatives that dbusiness model.

• Accelerate FCC exploration of innovative spectrum use anspectrum allocation.’’

http://pulver.com/press/powell.htmlhttp://www.pulver.com/products/sip/


elay (adapted from a drawing by Ciscoa)

avg (ms) max (ms) hops

0 4 221 21 21 128 39 44 1422 124 135 1599 199 200 2350 350 351 20

800 900 ms

elephony


Latency

For example:

Figure 2: Usability of a voice circuit as a function of end-to-end da. (this was at http://www.packeteer.com/solutions/voip/sld006.htm)

Round-trip times from dumburken.it.kth.se(as of 2004.03.26)

min (ms)

Local LANs (www.imit.kth.se) 0to northern Sweden (cdt-lisa.cdt.luth.se)to Austria (www.tu-graz.ac.at) 3To my machine in eastern US (via an SDSL link) 1To US west coast (www.stanford.edu) 1To Australia (www.uow.edu.au) {via the US west coast} 3

Usability

1

0100 200 300 400 500 600 700

Toll quality Satellite CB Radio

FAX relay/broadcast

Internet t(past)(now!)


tion

an operator

al/national network to the same

Maguire VOIP Modes of [email protected] 2006.03.12

VOIP Modes of Opera• PC to PC• PC-to-Telephone calls• Telephone-to-PC calls• Telephone-to-Telephone calls via the Internet• Premises to Premises

• use IP to tunnel from one PBX/Exchange to another• see Time Warner’s “Telecom One Solution”

• Premises to Network• use IP to tunnel from one PBX/Exchange to a gateway of

• Network to Network• from one operator to another or from one operator’s region

operator in another region or nation


tructure

AP Mobile

In-building WLAN system

Handset

Maguire IP based data+voice [email protected] 2006.03.12

IP based data+voice infras

exchange

Workstation

E-1 to PSTN AP

GatewayWorkstation

Router

Internet

Gateway

Voice

Handset

Handset

Public cells

Home

Office

FW/Switch

IP Phone


urrently (formerly?) used foror special purpose gateways such

LAN

LANadaptor

Maguire Voice [email protected] 2006.03.12

Voice Gateway

Use access servers filled with digital modems (ccurrent analog modem pools) as voice gatewaysas that of Li Wei [4].

CPU

Modem chip

2B+D or 30B+D or …

digital pathISDN interface

A/D converterD/A converter

Digitized voice or data


tewaysfax services, but can also enabletegrated messaging, least-cost

ce, encapsulate it into packets, and send itpressed, buffered, and then sent out as

world and the E.164 telephone numbering

ding/decoding or G.729

Maguire Voice over IP (VOIP) [email protected] 2006.03.12

Voice over IP (VOIP) GaGateways not only provide basic telephony and lots of value-added services, e.g., call-centers, inrouting, … .

Such gateways provide three basic functions:• Interface between the PSTN network and the Internet

Terminate incoming synchronous voice calls, compress the voias IP packets. Incoming IP voice packets are unpacked, decomsynchronous voice to the PSTN connection.

• Global directory mappingTranslate between the names and IP addresses of the Internetscheme of the PSTN network.

• Authentication and billing

Voice representation

Commonly: ITU G.723.1 algorithm for voice enco(CS-ACELP voice compression).


ventional signaling will be used

ly happens at thebeginningor what can be enabled via SIP

.

ntire FAX before

anagement Information Base)

yropped calls, lost/resent


Signaling

Based on the H.323 standard on the LAN and conon telephone networks.

NB: In conventional telephony networks signallingonandendof acall. See Theo Kanter’s dissertation fso that you can react toother events.Fax Support

Both store-and-forward and real-time fax modes

• In store-and-forward the system records the etransmission.

Management

Full SNMP management capabilities via MIBs (M

• provided to control all functions of the Gatewa• Extensive statistical data will be collected on d

packets, and network delays.


ch simpler than H.323


Compatibility

De jure standards:• ITU G 723.1/G.729 and H.323• VoIP Forum IA 1.0

De facto standards:• Netscape’s Cooltalk• Microsoft’s NetMeeting (formerly H.323, now SIP)

Session Initiation Protocol (SIP) [RFC 2543] is mu


IPoice traffic (e.g., telephone calls

rrying packetized audio and

Maguire Cisco’s Voice Over [email protected] 2006.03.12

Cisco’s Voice Over Enables Cisco 3600 series routers to carry live vand faxes) over an IP network.

They state that this could be used for:

• Toll bypass• Remote PBX presence over WANs• Unified voice/data trunking• POTS-Internet telephony gateways

Uses Real-Time Transport Protocol (RTP) for cavideo traffic over an IP network.

Cisco 3600 supports a selection of CODECs:

• G.711 A-Law 64,000 bits per second (bps)• G.711 u-Law 64,000 bps• G.729 8000 bps


ly need to send traffic if thereke this because it enables even

ey hearabsolute silence, so toise when there is nothing useful to generate backgroundated”.

e gateway with software such as


Cisco 3800 supports even more CODECs:

• ITU G.726 standard, 32k rate• ITU G.726 standard, 24k rate• ITU G.726 standard, 16k rate• ITU G.728 standard, 16k rate (default)• ITU G.729 standard, 8k rate

By using Voice Activity Detection (VAD) - you onis something to send {Note: telecom operators lihigher levels of statistical multiplexing}.

An interesting aspect is that users worry when thhelp make them comfortable it is useful to play noto output. Cisco provide a “comfort-noise commandnoise to fill silent gaps during calls if VAD is activ

Cisco 3600 series router can be used as the voicMicrosoft NetMeeting.


ates either current voice rate or

ed/113t/1


Cisco 3800 also supports “fax-relay” - at various r2,400/4,800/7,200/9,600/14,400 bps fax rates.

For futher information seehttp://www.cisco.com/univercd/cc/td/doc/product/software/ios11313t_1/voip/config.htm

http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113t/113t_1/voip/config.htm


stemco Systems announced thattVision™ wireless LAN handsetocal area network telephone

infrastructure and a voice system conforms to H.323.

rea network telephone

ming algorithm with load

eous, full-duplex phone calls.

s WebSwitch2000.

Maguire Intranet Telephone [email protected] 2006.03.12

Intranet Telephone SyOn January 19, 1998,Symbol Technologies and Cisthey had combined the Symbol Technologies’ Neand Cisco 3600 to provide a complete wireless lsystem based on Voice-Over-IP technology.

The handset uses a wireless LAN (IEEE 802.11)gateway via Cisco 3600 voice/ fax modules. The

"I believe that this is the first wireless local abased on this technology" -- Jeff Pulver

Seamless roaming via Symbol’s pre-emptive roabalancing.

Claims each cell can accommodate ~25 simultan

Ericsson partnered with Symbol, using Ericsson’

http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113t/113t_1/voip/config.htmhttp://www.symbol.com


sed data solutions through thewill primarily enhance Telia

t will lead to the introduction ofdata connections are currentlybe introduced.

ources it needs to maintain itsof radio-based LAN solutions.

edium-sized companies as well as bytions.

ducts that do not require frequencylace cabled data networks in,

phasis added by Maguire]

Maguire Wireless [email protected] 2006.03.12

Wireless LANs“The wireless workplace will soon be upon us1

Telia has strengthened its position within the area of radio-baacquisition of Global Cast Internetworking. The companyMobile’s offering in wireless LANs and develop solutions thathe wireless office. A number of different alternatives to fixedunder development and, later wireless IP telephony will also

…

The acquisition means that Telia Mobile has secured the rescontinued expansion and product development within the fieldRadio LANs are particularly suitable for use by small and moperators of public buildings such as airports and railway sta

Today’s radio-LAN technology is based on inexpensive procertification. They are easy to installand are often used to repfor example, large buildings.

…” [em

1. Telia press annoucement: 1999-01-25


orporate network from airports, centers, etc. via WLAN.

Maguire Telia’s [email protected] 2006.03.12

Telia’s HomeRunhttp://www.homerun.telia.com/

A subscription based service to link you to your ctrain stations, ferry terminals, hotels, conference

Look for Telia’s HomeRun logo:

http://www.homerun.telia.com/


Net"rated GSM- IP (Internet

applicationsea GSM coverage to

lications includeling, unified messagingharing using voice

Maguire Ericsson’s "GSM on the Net"[email protected] 2006.03.12

Ericsson’s "GSM on the• Provide communication services over an integ

Protocol) network• support local and global mobility• support multimedia capabilities and IP-based • uses small radio base stations to add local-ar

office LANs• provides computer-telephony integration: app

web-initiated telephony, directory-assisted diaand advanced conferencing and application-sdatacoms and video.


phonyfrom the US is via VoIP, basedia PSTN [10] (the article citesGroup/Primetrica Inc.)

plans for unlimited North

ce their exchanges with IPn, “Telia ersätter all AXE med05, page 4.

e [11].

Maguire VOIP vs. traditional [email protected] 2006.03.12

VOIP vs. traditional teleAs of 2003 approx. 14% of International traffic to/on 24 billions minutes vs. 170.7 billion minutes vthe source of data as TeleGeography Research

As of December 2004, commercial VoIP callingAmerican traffic cost ~US$20-30/month.

There is a move for traditional operators to replatelephony, see Niels Herbert and Göte AnderssoIP-telefoni”, Elektronik Tidningen, #3, 4 March 20

For information about the development of the AXE switches se


y Bart Stuck and Michaelolume 28, Number 8,August

ephony, and what is hype?

at in 1998, access arbitrage isticipate that switched-accessisappears and/or access rates

d data via packetized networkscosts. As a result, VOIP willd voice. Indeed, as voice/data

voice becoming economically

ion means that ISPs do not pay the ISP justreceives calls from


Economics“Can Carriers Make Money On IP Telephony?” bWeingarten, Business Communication Review, V1998, pp. 39-44.

"What is the reality in the battle over packet-versus-circuit tel

Looking at the potential savings by cost element, it is clear ththe major economic driver behind VOIP. By 2003, we anarbitrage will diminish in importance, as the ESP exemption ddrop to true underlying cost.

However, we believe that the convergence between voice anwill offset the disappearance of a gap in switched accesscontinue to enjoy a substantial advantage over circuit-switcheconvergence occurs, we see standalone circuit-switchednonviable."

Note: Enhanced Service Provider (ESP) exemptaccess charges to local phone companies {sinceusers}


honyuld carriers worry?”1 nicely

re ⇒ Content-neutralhe large margins which

d landline): $1.70/MB”

can offer phone services traffic

s2

can create a service

traditional telephony services.

uate Course "Internet Multimedia", University of Oulu, 3-6

Maguire VoIP vs. traditional [email protected] 2006.03.12

VoIP vs. traditional telepHenning Schulzrinne in a slide entitled “Why shostates the threats to traditional operators:

• Evolution from application-specific infrastructubandwidth delivery mechanism - takes away tthe operators are used to (and want !):

– “GPRS: $4-10/MB, SMS: >$62.50/MB, voice (mobile an

• Only operators can offer services ⇒ Anybody• SIP only needs to handle signaling, not media

• High barriers to entry ⇒ No regulatory hurdleIn addition to this we can add:

• Only vendors can create services ⇒ anybodyNB. These new services can be far broader than

1. Henning Schulzrinne, “When will the telephone network disappear?”, as part of Intensive GradJune 2002.

2. see “Regulations in Sweden” on page 76


t least this patent:

formation among a plurality ofrotocol contemplate first ands are coupled to both the firstpath and writes another signalhich electrically precedes thensmitted in a regular, cycliccycle code for enabling eachket to transmit, it can read theo, a logical interpretation may

oice and data transmission


PatentsMixing voice and data in the LAN goes back to a

ABSTRACT: In order to control the transfer of packets of instations, the instant communications system, station and psecond oppositely directed signal paths. At least two stationand the second signal paths. A station reads one signal from aon the path. The one signal is read by an arrangement warrangement for writing the other signal. Packets are trasequence. A head station on a forward path writes a startstation to transmit one or more packets. If a station has a pacbus field of a packet on the forward path. Responsive theret

US 4581735 : Local area network packet protocol for combined v

INVENTORS: Lois E. Flamm and John O. Limb

ASSIGNEES: AT&T Bell Laboratories, Murray Hill, NJ

ISSUED: Apr. 8 , 1986

FILED: May 31,1983


sy. If the path is not busy, theereon including the busy field.ath is detected as not busy. Ination may write different startble stations to transmit voicemit data packets, etc. for the

be written in a regular, e.g.,h clipping. Still further, the lastackets on a reverse path forResponsive to the control

the respective stations to, fore number of packet time slots,


be made as to whether the forward path is busy or is not bupacket may be written on the path by overwriting any signal thIf the path is busy, the station may defer the writing until the porder to accommodate different types of traffic, the head stcycle codes. For example, a start-of-voice code may enapackets; a start-of-data code may enable stations to transdifferent types of traffic. Further, the start cycle codes mayperiodic, fashion to mitigate deleterious effects, such as speecstation on the forward path may write end cycle codes in pcommunicating control information to the head station.information, the head station may modify the cycle to permitexample, transmit more than one packet per cycle or to vary thwhich are allocated to each of the different types of traffic.


nds


IPing voice-over-frame relay service in 40ending voice traffic over its frame relayHuntley, executive VP of marketing for

c over data networks. Most of the major

US$3-4/month US$50-60/month for unlimiteds not include equipment attion} The Service Level5ms round trip latency, and

e US for US$34.95/monthe future will be about thehere these two worlds meet is

y,1/98.

Maguire Carriers offering [email protected] 2006.03.12

Carriers offering VO“Equant, a network services provider, will announce tomorrow that it is introduccountries, ... The company says customers can save 20% to 40% or more by snetwork. "This is the nearest you’re going to get to free voice," says LaurenceEquant Network Service. … Equant isn’t alone in its pursuit to send voice traffi

carriers are testing services that would send voice over data networks. ... .”1

• October 2002:• Verizon offering managed IP telephony via IPT Watch for • WorldCom offering SIP based VoIP for DSL customers for

local, domestic long distance, and data support {price doeUS$200-300 per phone and DSL/Frame relay/ATM connecAgreement (SLA) specifies >99.9% network availability, 99.5% packet delivery.

• December 2004:• Verizon offering VoiceWing - with unlimited calling within th• “As we see the industry fundamentals continue to shift, th

convergence of computing and telecommunications. And wwhere MCI will be.” -- Michael D. Capellas, MCI CEO 2

1. Mary E. Thyfault, Equant To Roll Out Voice-Over-Frame Relay Service, InformationWeek Dail10/2

2. http://global.mci.com/about/publicpolicy/voip/

http://global.mci.com/about/publicpolicy/voip/


onnection

its own staff!)

lly 1+ move/person/year)

yond the LAN to the WANtilize a Web browser to

nt, thus limiting

uipment (CPE)

Maguire MCI (formerly WorldCom) [email protected] 2006.03.12

MCI (formerly WorldCom) CPreviously

• 3 or more separate networks (often each had • Duration/geography-based pricing

• Expensive moves, adds, and changes (typica• Standalone applications - generally expensive• Closed PBX architectureToday

• via gateway to the PSTN, service expands be• centralized intelligence is offered; customers u

control and manage their network• MCI incurs the costs of buying major equipme

customer’s risk and capital investment• One source for all services• Easy mobility• Choice of vendors for Customer Premises Eq


s Inc.alling service across the Unitedoice over Internet protocol

Offerings, Internetweek.com,January 13, 2004,

ticle.jhtml?articleID=17300739

VoIP and data services to their

voice signals from the PSTNoice signals when a call is routed

of calls per month - as of

Maguire Level 3 Communications [email protected] 2006.03.12

Level 3 CommunicationIntroduced (3)VoIP Toll Free service: “a toll-free cStates, rounding out its local and long distance vofferings.”

Antone Gonsalves, E-BUSINESS: Level 3 Rounds Out VoIP

http://www.internetweek.com/e-business/showAr

Level 3 sells services to carriers, who then offer customers.

Usessoftswitch networking technology to convertto IP packets and conversely converts packets to v

to the public switched network. (>30 x 109 minutes January 13, 2005)


elefoniential broadband telephonytsip AB (www.hotsip.com ). In calls, presence, and instant

st 80 kr. price as if you calledork.area/city” code 075 (i.e.,

00-numbers)

Maguire TeliaSonera [email protected] 2006.03.12

TeliaSonera BredbandstFebruary 5th, 2004 TeliaSonera annouces theirresidservice using server and client products from Hoaddition to telephony, the service includes: videomessaging.[6]

• The startup cost is 250 kr and the monthly co• Calls to the fixed PSTN network are the same

from a fixed telephone in their traditional netw• Customers get a telephone number from the “

+46 75-15xxxxxxx)• They do not support calls to “betalsamtal” (09

www.hotsip.com


Nff” when it can really emulateSTN:

strings}

Maguire Emulating the [email protected] 2006.03.12

Emulating the PSTMany people feel that VoIP will really only “take oall the functions which users are used to in the P

• Integration with the web via: Click-to-connect• “Dialing” an e-mail address or URL {digits vs. • Intelligent network (IN) services:

• Call forward, busy• Call forward, no ans.• Call forward, uncond.• Call hold• Call park• Call pick-up• Call waiting• Consultation hold• Do not disturb• Find-me• Incoming call screen/Outgoing call screen• Secondary number in/Secondary number out• Three-way conference• Unattended transfer


ans providing functionstil 31 August 2005”)ng Desktop calles, etc.asing use of Power over the wall outlet does not

location of the station?}

Maguire Emulating the [email protected] 2006.03.12

• additional PBX features (which in Sweden mesuch as “I’m on vacation and will not return un

• Computer-Telephony Integration (CTI), includimanagement, integration with various databas

• PSTN availability and reliability (thus the increEthernet for ethernet attached IP phones - sohave to provide power for the phone to work)

• Roaming - both personal and device mobility• Phone number portability• E911 service {How do you handle geographic


turesl

ld be the target of a call

Maguire Calling and Called [email protected] 2006.03.12

Calling and Called Fea• Calling feature - activated when placing a cal

• e.g., Call Blocking and Call Return

• Called feature - activated when this entity wou• Call Screening and Call Forward

aging Module 1: 71 of 84Practical Voice Over IP (VoIP): SIP and related protocols

& Instant

traveling, …

ce, video, …

nce and Instant Communications), Protocols, and Applications.

ssaging platform for thers each week.

oyees - an experimentalging (IM), email, voice,

Maguire Beyond the PSTN: Presence & Instant [email protected] 2006.03.12

Beyond the PSTN: PresenceMessaging

• Presence , i.e., Who is available?• Location , i.e., Where are they?: office, home,• Call state : Are they busy (in a call) or not?• Willingness : Are they available or not?• Preferred medium : text message, e-mail, voi• Preferences (caller and callee preferences)

See Sinnreich and Johnston’s Chapter 11 (Prese& course2G5565 Mobile Presence: Architectures

• Reuters has deployed a SIP-based instant-mefinancial services industry that has 50,000 use

• IBM’s NotesBuddy application for ~315k emplmessaging client that integrates instant messaand other communication.


vices

onal time”

roup chat sessions, …f people are all available

his is a good area fortures, Protocols, and

ensions (SIMPLE)

Maguire Presence-Enabled [email protected] 2006.03.12

Presence-Enabled Ser• Complex call screening

• Location-based: home vs. work• Caller-based: personal friend or business colleague• Time-based: during my “working hours” or during my “pers

• Join an existing call ⇒ Instant Conferencing, g• Creating a conference when a specific group o

and willing to be called• New services that have yet to be invented! (T

projects in 2G5565 Mobile Presence: ArchitecApplications)

• SIP Messaging and Presence Leveraging ExtWorking Group was formed in March 2001http://www.ietf.org/html.charters/simple-charter.html

http://www.ietf.org/html.charters/simple-charter.html


for VoIP

handsets controlled by thees onany platform

edia contentin digital form

s

Implementation

H.323

Softswitches

ession Initiation Protocol (SIP)

Maguire Three major alternatives for [email protected] 2006.03.12

Three major alternatives

SIP⇒ a change from telephony’s “calls” betweennetwork to “sessions” which can be betweenprocessanywherein the Internet and with bothcontrol andmand hence can be easily manipulated.

• thus a separate voice network is not necessary• open and distributed nature enables lots of innovation

– since both control and media can be manipulated and– “events” are no longer restricted to start and end of call

Concept

Usesignalling concepts from the traditional telephony industry

Usecontrol concepts from the tr

2G1325/2G5564 Practical Voice Over IP (VoIP): SIP and ......Maguire 2 of 22 [email protected] 2006.03.12 Practical Voice Over IP (VoIP): SIP and related protocols Module 1: Introduction.....

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