SIP: Understanding the Session Initiation Protocol Third Edition -- Contents -- Foreword to the First Edition -- Preface to the Third Edition -- Preface to the Second Edition -- Preface to the First Edition -- 1 SIP and the Internet -- 1.1 Signaling Protocols -- 1.2 Internet Multimedia Protocol Stack -- 1.2.1 Physical Layer -- 1.2.2 Data/Link Layer -- 1.2.3 Network Layer -- 1.2.4 Transport Layer -- 1.2.5 Application Layer -- 1.2.6 Utility Applications -- 1.2.7 Multicast -- 1.3 Internet Names -- 1.4 URLs, URIs, and URNs -- 1.5 Domain Name Service -- 1.5.1 DNS Resource Records -- 1.5.2 Address Resource Records (A or AAAA) -- 1.5.3 Service Resource Records (SRV) -- 1.5.4 Naming Authority Pointer Resource Records (NAPTR) -- 1.5.5 DNS Resolvers -- 1.6 Global Open Standards -- 1.7 Internet Standards Process -- 1.8 A Brief History of SIP -- 1.9 Conclusion -- References -- 2 Introduction to SIP -- 2.1 A Simple Session Establishment Example -- 2.2 SIP Call with a Proxy Server -- 2.3 SIP Registration Example -- 2.4 SIP Presence and Instant Message Example -- 2.5 Message Transport -- 2.5.1 UDP Transport -- 2.5.2 TCP Transport -- 2.5.3 TLS Transport -- 2.5.4 SCTP Transport -- 2.6 Transport Protocol Selection -- 2.7 Conclusion -- 2.8 Questions -- References -- 3 SIP Clients and Servers -- 3.1 SIP User Agents -- 3.2 Presence Agents -- 3.3 Back-to-Back User Agents -- 3.4 SIP Gateways -- 3.5 SIP Servers -- 3.5.1 Proxy Servers -- 3.5.2 Redirect Servers -- 3.5.3 Registrar Servers -- 3.6 Uniform Resource Indicators -- 3.7 Acknowledgment of Messages -- 3.8 Reliability -- 3.9 Multicast Support -- 3.10 Conclusion -- 3.11 Questions -- References -- 4 SIP Request Messages -- 4.1 Methods -- 4.1.1 INVITE -- 4.1.2 REGISTER -- 4.1.3 BYE -- 4.1.4 ACK -- 4.1.5 CANCEL -- 4.1.6 OPTIONS -- 4.1.7 SUBSCRIBE -- 4.1.8 NOTIFY -- 4.1.9 PUBLISH -- 4.1.10 REFER -- 4.1.11 MESSAGE.

4.1.12 INFO -- 4.1.13 PRACK -- 4.1.14 UPDATE -- 4.2 URI and URL Schemes Used by SIP -- 4.2.1 SIP and SIPS URIs -- 4.2.2 Telephone URLs -- 4.2.3 Presence and Instant Messaging URLs -- 4.3 Tags -- 4.4 Message Bodies -- 4.5 Conclusion -- 4.6 Questions -- References -- 5 SIP Response Messages -- 5.1 Informational -- 5.1.1 100 Trying -- 5.1.2 180 Ringing -- 5.1.3 181 Call is Being Forwarded -- 5.1.4 182 Call Queued -- 5.1.5 183 Session Progress -- 5.2 Success -- 5.2.1 200 OK -- 5.2.2 202 Accepted -- 5.2.3 204 No Notifi cation -- 5.3 Redirection -- 5.3.1 300 Multiple Choices -- 5.3.2 301 Moved Permanently -- 5.3.3 302 Moved Temporarily -- 5.3.4 305 Use Proxy -- 5.3.5 380 Alternative Service -- 5.4 Client Error -- 5.4.1 400 Bad Request -- 5.4.2 401 Unauthorized -- 5.4.3 402 Payment Required -- 5.4.4 403 Forbidden -- 5.4.5 404 Not Found -- 5.4.6 405 Method Not Allowed -- 5.4.7 406 Not Acceptable -- 5.4.8 407 Proxy Authentication Required -- 5.4.9 408 Request Timeout -- 5.4.10 409 Confl ict -- 5.4.11 410 Gone -- 5.4.12 411 Length Required -- 5.4.13 412 Conditional Request Failed -- 5.4.14 413 Request Entity Too Large -- 5.4.15 414 Request-URI Too Long -- 5.4.16 415 Unsupported Media Type -- 5.4.17 416 Unsupported URI Scheme -- 5.4.18 417 Unknown Resource Priority -- 5.4.19 420 Bad Extension -- 5.4.20 421 Extension Required -- 5.4.21 422 Session Timer Interval Too Small -- 5.4.22 423 Interval Too Brief -- 5.4.23 428 Use Identity Header -- 5.4.24 429 Provide Referror Identity -- 5.4.25 430 Flow Failed -- 5.4.26 433 Anonymity Disallowed -- 5.4.27 436 Bad Identity-Info Header -- 5.4.28 437 Unsupported Certifi cate -- 5.4.29 438 Invalid Identity Header -- 5.4.30 439 First Hop Lacks Outbound Support -- 5.4.31 440 Max-Breadth Exceeded -- 5.4.32 470 Consent Needed -- 5.4.33 480 Temporarily Unavailable -- 5.4.34 481 Dialog/Transaction Does Not Exist.

5.4.35 482 Loop Detected -- 5.4.36 483 Too Many Hops -- 5.4.37 484 Address Incomplete -- 5.4.38 485 Ambiguous -- 5.4.39 486 Busy Here -- 5.4.40 487 Request Terminated -- 5.4.41 488 Not Acceptable Here -- 5.4.42 489 Bad Event -- 5.4.43 491 Request Pending -- 5.4.44 493 Request Undecipherable -- 5.4.45 494 Security Agreement Required -- 5.5 Server Error -- 5.5.1 500 Server Internal Error -- 5.5.2 501 Not Implemented -- 5.5.3 502 Bad Gateway -- 5.5.4 503 Service Unavailable -- 5.5.5 504 Gateway Timeout -- 5.5.6 505 Version Not Supported -- 5.5.7 513 Message Too Large -- 5.5.8 580 Preconditions Failure -- 5.6 Global Error -- 5.6.1 600 Busy Everywhere -- 5.6.2 603 Decline -- 5.6.3 604 Does Not Exist Anywhere -- 5.6.4 606 Not Acceptable -- 5.7 Questions -- References -- 6 SIP Header Fields -- 6.1 Request and Response Header Fields -- 6.1.1 Accept -- 6.1.2 Accept-Encoding -- 6.1.3 Accept-Language -- 6.1.4 Alert-Info -- 6.1.5 Allow -- 6.1.6 Allow-Events -- 6.1.7 Answer-Mode -- 6.1.8 Call-ID -- 6.1.9 Contact -- 6.1.10 CSeq -- 6.1.11 Date -- 6.1.12 Encryption -- 6.1.13 Expires -- 6.1.14 From -- Untitled -- 6.1.15 History Info -- 6.1.16 Organization -- 6.1.17 Path -- 6.1.18 Priv-Answer-Mod -- 6.1.19 Record-Route -- 6.1.20 Recv-Info -- 6.1.21 Refer-Sub -- 6.1.22 Retry-After -- 6.1.23 Subject -- 6.1.24 Supported -- 6.1.25 Timestamp -- 6.1.26 To -- 6.1.27 User-Agent -- 6.1.28 Via -- 6.2 Request Header Fields -- 6.2.1 Accept-Contact -- 6.2.2 Authorization -- 6.2.3 Call-Info -- 6.2.4 Event -- 6.2.5 Hide -- 6.2.6 Identity -- 6.2.7 Identity-Info -- 6.2.8 In-Reply-To -- 6.2.9 Info-Package -- 6.2.10 Join -- 6.2.11 Priority -- 6.2.12 Privacy -- 6.2.13 Proxy-Authorization -- 6.2.14 Proxy-Require -- 6.2.15 P-OSP-Auth-Token -- 6.2.16 P-Asserted-Identity -- 6.2.17 P-Preferred-Identity -- 6.2.18 Max-Breadth -- 6.2.19 Max-Forwards -- 6.2.20 Reason -- 6.2.21 Refer-To.

6.2.22 Referred-By -- 6.2.23 Reply-To -- 6.2.24 Replaces -- 6.2.25 Reject-Contact -- 6.2.26 Request-Disposition -- 6.2.27 Require -- 6.2.28 Resource-Priority -- 6.2.29 Response-Key -- 6.2.30 Route -- 6.2.31 RAck -- 6.2.32 Security-Client -- 6.2.33 Security-Verify -- 6.2.34 Session-Expires -- 6.2.35 SIP-If-Match -- 6.2.36 Subscription-State -- 6.2.37 Suppress-If-Match -- 6.2.38 Target-Dialog -- 6.2.39 Trigger-Consent -- 6.3 Response Header Fields -- 6.3.1 Accept-Resource-Priority -- 6.3.2 Authentication-Info -- 6.3.3 Error-Info -- 6.3.4 Flow-Timer -- 6.3.5 Min-Expires -- 6.3.6 Min-SE -- 6.3.7 Permission-Missing -- 6.3.8 Proxy-Authenticate -- 6.3.9 Security-Server -- 6.3.10 Server -- 6.3.11 Service-Route -- 6.3.12 SIP-ETag -- 6.3.13 Unsupported -- 6.3.14 Warning -- 6.3.15 WWW-Authenticate -- 6.3.16 RSeq -- 6.4 Message Body Header Fields -- 6.4.1 Content-Encoding -- 6.4.2 Content-Disposition -- 6.4.3 Content-Language -- 6.4.4 Content-Length -- 6.4.5 Content-Type -- 6.4.6 MIME-Version -- 6.5 Questions -- References -- 7 Wireless, Mobility, and IMS -- 7.1 IP Mobility -- 7.2 SIP Mobility -- 7.3 IMS and SIP -- 7.4 IMS Header Fields -- 7.5 Conclusion -- 7.6 Questions -- References -- 8 Presence and Instant Messaging -- 8.1 Introduction -- 8.2 History of IM and Presence -- 8.3 SIMPLE -- 8.4 Presence with SIMPLE -- 8.4.1 SIP Events Framework -- 8.4.2 Presence Bodies -- 8.4.3 Resource Lists -- 8.4.4 Filtering -- 8.4.5 Conditional Event Notifi cations and ETags -- 8.4.6 Partial Publication -- 8.4.7 Presence Documents Summary -- 8.5 Instant Messaging with SIMPLE -- 8.5.1 Page Mode Instant Messaging -- 8.5.2 Common Profi le for Instant Messaging -- 8.5.3 Instant Messaging Delivery Notifi cation -- 8.5.4 Message Composition Indication -- 8.5.5 Multiple Recipient Messages -- 8.5.6 Session Mode Instant Messaging -- 8.6 Jabber.

8.6.1 Standardization as Extensible Messaging and Presence Protocol -- 8.6.2 Interworking with SIMPLE -- 8.6.3 Jingle -- 8.6.4 Future Standardization of XMPP -- 8.7 Conclusion -- 8.8 Questions -- References -- 9 Services in SIP -- 9.1 Gateway Services -- 9.2 SIP Trunking -- 9.3 SIP Service Examples -- 9.4 Voicemail -- 9.5 SIP Video -- 9.6 Facsimile -- 9.7 Conferencing -- 9.7.1 Focus -- 9.7.2 Mixer -- 9.7.3 Non-SIP Conference Control -- 9.8 Application Sequencing -- 9.9 Other SIP Service Architectures -- 9.9.1 Service Oriented Architecture -- 9.9.2 Servlets -- 9.9.3 Service Delivery Platform -- 9.10 Conclusion -- 9.11 Questions -- References -- 10 Network Address Translation -- 10.1 Introduction to NAT -- 10.2 Advantages of NAT -- 10.3 Disadvantages of NAT -- 10.4 How NAT Works -- 10.5 Types of NAT -- 10.5.1 Endpoint Independent Mapping NAT -- 10.5.2 Address Dependent Mapping NAT -- 10.5.3 Address and Port Dependent Mapping NAT -- 10.5.4 Hairpinning Support -- 10.5.5 IP Address Pooling Options -- 10.5.6 Port Assignment Options -- 10.5.7 Mapping Refresh -- 10.5.8 Filtering Modes -- 10.6 NAT Mapping Examples -- 10.7 NATs and SIP -- 10.8 Properties of a Friendly NAT or How a NAT Should BEHAVE -- 10.9 STUN Protocol -- 10.10 UNSAF Requirements -- 10.11 SIP Problems with NAT -- 10.11.1 Symmetric SIP -- 10.11.2 Connection Reuse -- 10.11.3 SIP Outbound -- 10.12 Media NAT Traversal Solutions -- 10.12.1 Symmetric RTP -- 10.12.2 RTCP Attribute -- 10.12.3 Self-Fixing Approach -- 10.13 Hole Punching -- 10.14 TURN: Traversal Using Relays Around NAT -- 10.15 ICE: Interactive Connectivity Establishment -- 10.16 Conclusion -- 10.17 Questions -- References -- 11 Related Protocols -- 11.1 PSTN Protocols -- 11.1.1 Circuit Associated Signaling -- 11.1.2 ISDN Signaling -- 11.1.3 ISUP Signaling -- 11.2 SIP for Telephones -- 11.3 Media Gateway Control Protocols -- 11.4 H.323.

11.4.1 Introduction to H.323.