1. May 23, 2005Alcatel1 Advanced Multimedia and Presence Services using Classical and P2P SIP Henning Schulzrinne (with Kundan Singh, Ron Shacham, Xiaotao Wu, Jonathan Lennox and others) Department of Computer Science Columbia University hgs@cs.columbia.edu Alcatel May 23, 2005

2. Alcatel2 Overview Quick overview of SIP Ring-and-hope  presence-mediated communications Uses for presence: Old: “I’m on-line” Location-based services Presence-derived call handling Presence-derived trust Presence and privacy Service and session mobility Application sharing

3. May 23, 2005 Alcatel3 Philosophy transition One computer, many users One computer, one user Many computers, one user anywhere, any time any media right place (device), right time, right media ~ ubiquitous computing mainframe era

4. May 23, 2005 Alcatel4 Evolution of VoIP “amazing – the phone rings” “does it do call transfer?” “how can I make it stop ringing?” 1996-2000 2000-20032004- catching up with the digital PBX long-distance calling, ca. 1930 going beyond the black phone

5. May 23, 2005 Alcatel5 Collaboration in transition intra-organization; small number of systems (meeting rooms) inter-organization multiple technology generations diverse end points proprietary (single- vendor) systems standards-based solutions

6. May 23, 2005 Alcatel6 SIP Overview

7. May 23, 2005 Alcatel7 Internet services – the missing entry Service/deliverysynchronousasynchronous pushinstant messaging presence event notification session setup media-on-demand messaging pulldata retrieval file download remote procedure call peer-to-peer file sharing

8. May 23, 2005 Alcatel8 Filling in the protocol gap Service/deliverysynchronousasynchronous pushSIP RTSP, RTP SMTP pullHTTP ftp SunRPC, Corba, SOAP (not yet standardized)

9. May 23, 2005 Alcatel9 SIP as service enabler Rendezvous protocol lets users find each other by only knowing a permanent identifier Mobility enabler: personal mobility one person, multiple terminals terminal mobility one terminal, multiple IP addresses session mobility one user, multiple terminals in sequence or in parallel service mobility services move with user

10. May 23, 2005 Alcatel10 What is SIP? Session Initiation Protocol  protocol that establishes, manages (multimedia) sessions also used for IM, presence & event notification uses SDP to describe multimedia sessions Developed at Columbia U. (with others) Standardized by IETF (RFC 3261-3265 et al) 3GPP (for 3G wireless) PacketCable About 100 companies produce SIP products Microsoft’s Windows Messenger (≥4.7) includes SIP

11. May 23, 2005 Alcatel11 Philosophy Session establishment & event notification Any session type, from audio to circuit emulation Provides application-layer anycast service Provides terminal and session mobility Based on HTTP in syntax, but different in protocol operation Peer-to-peer system, with optional support by proxies even stateful proxies only keep transaction state, not call (session, dialogue) state transaction: single request + retransmissions proxies can be completely stateless

12. May 23, 2005 Alcatel12 Basic SIP message flow

13. May 23, 2005 Alcatel13 SIP trapezoid outbound proxy a@foo.com: 128.59.16.1 registrar 1 st request 2 nd, 3 rd, … request voice traffic RTP destination proxy (identified by SIP URI domain)

14. May 23, 2005 Alcatel14 SIP message format SDP INVITE sip:bob@there.com SIP/2.0 Via: SIP/2.0/UDP here.com:5060 From: Alice To: Bob Call-ID: 1234@here.com CSeq: 1 INVITE Subject: just testing Contact: sip:alice@pc.here.com Content-Type: application/sdp Content-Length: 147 v=0 o=alice 2890844526 2890844526 IN IP4 here.com s=Session SDP c=IN IP4 100.101.102.103 t=0 0 m=audio 49172 RTP/AVP 0 a=rtpmap:0 PCMU/8000 SIP/2.0 200 OK Via: SIP/2.0/UDP here.com:5060 From: Alice To: Bob Call-ID: 1234@here.com CSeq: 1 INVITE Subject: just testing Contact: sip:alice@pc.here.com Content-Type: application/sdp Content-Length: 134 v=0 o=bob 2890844527 2890844527 IN IP4 there.com s=Session SDP c=IN IP4 110.111.112.113 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 message body header fields request line request response

15. May 23, 2005 Alcatel15 PSTN vs. Internet Telephony Signaling & Media Signaling Media PSTN: Internet telephony: China Belgian customer, currently visiting US Australia

16. May 23, 2005 Alcatel16 SIP addressing Users identified by SIP or tel URIs sip:alice@example.com tel: URIs describe E.164 number, not dialed digits (RFC 2806bis) tel URIs  SIP URIs by outbound proxy A person can have any number of SIP URIs The same SIP URI can reach many different phones, in different networks sequential & parallel forking SIP URIs can be created dynamically: GRUUs conferences device identifiers (sip:foo@128.59.16.15) Registration binds SIP URIs (e.g., device addresses) to SIP “address-of-record” (AOR) tel:110 sip:sos@domain domain  128.59.16.17 via NAPTR + SRV

17. May 23, 2005 Alcatel17 3G Architecture (Registration) visited IM domain home IM domain serving CSCF interrogating proxy interrogating mobility management signaling registration signaling (SIP)_

18. May 23, 2005 Alcatel18 SIP is PBX/Centrex ready call waiting/multiple calls RFC 3261 holdRFC 3264 transferRFC 3515/Replaces conferenceRFC 3261/callee caps message waitingmessage summary package call forwardRFC 3261 call parkRFC 3515/Replaces call pickupReplaces do not disturbRFC 3261 call coverageRFC 3261 from Rohan Mahy’s VON Fall 2003 talk simultaneous ringing RFC 3261 basic shared linesdialog/reg. package barge-inJoin “Take”Replaces Shared-line “privacy” dialog package divert to adminRFC 3261 intercomURI convention auto attendantRFC 3261/2833 attendant consoledialog package night serviceRFC 3261 centrex-style features boss/admin features attendant features

19. May 23, 2005 Alcatel19 A constellation of SIP RFCs Resource mgt. (3312) Reliable prov. (3262) INFO (2976) UPDATE (3311) Reason (3326) SIP (3261) DNS for SIP (3263) Events (3265) REFER (3515) DHCP (3361) DHCPv6 (3319) Digest AKA (3310) Privacy (3323) P-Asserted (3325) Agreement (3329) Media auth. (3313) AES (3853) Non-adjacent (3327) Symmetric resp. (3581) Service route (3608) User agent caps (3840) Caller prefs (3841) ISUP (3204) sipfrag (3240) Security & privacy Configuration Core Mostly PSTN Content types Request routing

20. May 23, 2005 Alcatel20 An eco system, not just a protocol SIP XCAP (config) RTSP SIMPLE policy RPID …. SDP XCON (conferencing) STUN TURN RTP configures initiatescarries controls provide addresses

21. May 23, 2005 Alcatel21 SIP – a bi-cultural protocol overlap dialing DTMF carriage key systems notion of lines per-minute billing early media ISUP & BICC interoperation trusted service providers multimedia IM and presence location-based service user-created services decentralized operation everyone equally suspect

22. May 23, 2005 Alcatel22 Context-aware communication context = “the interrelated conditions in which something exists or occurs” anything known about the participants in the (potential) communication relationship both at caller and callee timeCPL capabilitiescaller preferences locationlocation-based call routing location events activity/availabilitypresence sensor data (mood, bio)privacy issues similar to location data

23. May 23, 2005 Alcatel23 GEOPRIV and SIMPLE architectures target location server location recipient rule maker presentity caller presence agent watcher callee GEOPRIV SIP presence SIP call PUBLISH NOTIFY SUBSCRIBE INVITE publication interface notification interface XCAP (rules) INVITE DHCP

24. May 23, 2005 Alcatel24 The role of presence Guess-and-ring high probability of failure: “telephone tag” inappropriate time (call during meeting) inappropriate media (audio in public place) current solutions: voice mail  tedious, doesn’t scale, hard to search and catalogue, no indication of when call might be returned automated call back  rarely used, too inflexible  most successful calls are now scheduled by email Presence-based facilitates unscheduled communications provide recipient-specific information only contact in real-time if destination is willing and able appropriately use synchronous vs. asynchronous communication guide media use (text vs. audio) predict availability in the near future (timed presence) Prediction: almost all (professional) communication will be presence-initiated or pre-scheduled

25. May 23, 2005 Alcatel25 Basic presence Role of presence initially: “can I send an instant message and expect a response?” now: “should I use voice or IM? is my call going to interrupt a meeting? is the callee awake?” Yahoo, MSN, Skype presence services: on-line & off-line useful in modem days – but many people are (technically) on-line 24x7 thus, need to provide more context + simple status (“not at my desk”) entered manually  rarely correct does not provide enough context for directing interactive communications

26. May 23, 2005 Alcatel26 Presence data architecture raw presence document create view (compose) privacy filtering draft-ietf-simple-presence-data-model composition policy privacy policy presence sources XCAP (not defined yet) depends on watcher select best source resolve contradictions PUBLISH

27. May 23, 2005 Alcatel27 Presence data architecture candidate presence document watcher filter raw presence document post-processing composition (merging) final presence document difference to previous notification SUBSCRIBE NOTIFY remove data not of interest watcher

28. May 23, 2005 Alcatel28 Presence data model “calendar”“cell”“manual” alice@example.com audio, video, text r42@example.com video person (presentity) (views) services devices

29. May 23, 2005 Alcatel29 Rich presence More information automatically derived from sensors: physical presence, movement electronic activity: calendars Rich information: multiple contacts per presentity device (cell, PDA, phone, …) service (“audio”) activities, current and planned surroundings (noise, privacy, vehicle, …) contact information composing (typing, recording audio/video IM, …)

30. May 23, 2005 Alcatel30 RPID: rich presence

31. May 23, 2005 Alcatel31 RPID = rich presence Provide watchers with better information about the what, where, how of presentities facilitate appropriate communications: “wait until end of meeting” “use text messaging instead of phone call” “make quick call before flight takes off” designed to be derivable from calendar information or provided by sensors in the environment allow filtering by “sphere” – the parts of our life don’t show recreation details to colleagues

32. May 23, 2005 Alcatel32 CIPID: Contact Information More long-term identification of contacts Elements: card – contact Information home page icon – to represent user map – pointer to map for user sound – presentity is available

33. May 23, 2005 Alcatel33 The role of presence for call routing Two modes: watcher uses presence information to select suitable contacts advisory – caller may not adhere to suggestions and still call when you’re in a meeting user call routing policy informed by presence likely less flexible – machine intelligence “if activities indicate meeting, route to tuple indicating assistant” “try most-recently-active contact first” (seq. forking) LESS translate RPID CPL PA PUBLISH NOTIFY INVITE

34. May 23, 2005 Alcatel34 Presence and privacy All presence data, particularly location, is highly sensitive Basic location object (PIDF-LO) describes distribution (binary) retention duration Policy rules for more detailed access control who can subscribe to my presence who can see what when <gml:Point gml:id="point1“ srsName="epsg:4326"> 37:46:30N 122:25:10W no 2003-06-23T04:57:29Z 2003-06-22T20:57:29Z

35. May 23, 2005 Alcatel35 Privacy policy relationships geopriv-specificpresence-specific common policy RPIDCIPID future

36. May 23, 2005 Alcatel36 Privacy rules Conditions identity, sphere time of day current location identity as or + Actions watcher confirmation Transformations include information reduced accuracy User gets maximum of permissions across all matching rules privacy-safe composition: removal of a rule can only reduce privileges Extendable to new presence data rich presence biological sensors mood sensors

37. May 23, 2005 Alcatel37 Example rules document user@example.com allow sip mailto true bare

38. May 23, 2005 Alcatel38 Creating and manipulating rules Uploaded in whole or part via XCAP XML not user-visible Web or application UI, similar to mail filtering Can also be location-dependent “if at home, colleagues don’t get presence information” Possibly implementation-defined “privacy levels”

39. May 23, 2005 Alcatel39 Location-based services Finding services based on location physical services (stores, restaurants, ATMs, …) electronic services (media I/O, printer, display, …) not covered here Using location to improve (network) services communication incoming communications changes based on where I am configuration devices in room adapt to their current users awareness others are (selectively) made aware of my location security proximity grants temporary access to local resources

40. May 23, 2005 Alcatel40 Location-based SIP services Location-aware inbound routing do not forward call if time at callee location is [11 pm, 8 am] only forward time-for-lunch if destination is on campus do not ring phone if I’m in a theater outbound call routing contact nearest emergency call center send delivery@pizza.com to nearest branchdelivery@pizza.com location-based events subscribe to locations, not people Alice has entered the meeting room subscriber may be device in room  our lab stereo changes CDs for each person that enters the room

41. May 23, 2005 Alcatel41 Location detection

42. May 23, 2005 Alcatel42 DHCP for locations modified dhcpd (ISC) to generate location information use MAC address backtracing to get location information DHCP server 458/17  Rm. 815 458/18  Rm. 816 DHCP answer: sta=DC loc=Rm815 lat=38.89868 long=77.03723 8:0:20:ab:d5:d CDP + SNMP 8:0:20:ab:d5:d  458/17

43. May 23, 2005 Alcatel43 Location-based service language false true NOTIFY action alert conditions proximity occupancy time IM actions alert message log call transfer join events incoming outgoing notify message subscription

44. May 23, 2005 Alcatel44 Program location-based services

45. May 23, 2005 Alcatel45

46. May 23, 2005 Alcatel46 Tracking

47. May 23, 2005 Alcatel47 Internet2 WG PIC trial PUBLISH presence status NOTIFY myself and others’ locations SUBSCRIBE to my location

48. May 23, 2005 Alcatel48 Example: user-adaptive device configuration “all devices that are in the building” RFC 3082? PA device controller SUBSCRIBE to each room SUBSCRIBE to configuration for users currently in rooms 1.discover room URI 2.REGISTER as contact for room URI tftp HTTP SLP 802.11 signal strength  location REGISTER To: 815cepsr Contact: alice@cs SIP room 815

49. May 23, 2005 Alcatel49 Session mobility Walk into office, switch from cell phone to desk phone call transfer problem  SIP REFER related problem: split session across end devices e.g., wall display + desk phone + PC for collaborative application assume devices (or stand-ins) are SIP- enabled third-party call control

50. May 23, 2005 Alcatel50 How to find services? Two complementary developments: smaller devices carried on user instead of stationary devices devices that can be time-shared large plasma displays projector hi-res cameras echo-canceling speaker systems wide-area network access Need to discover services in local environment SLP (Service Location Protocol) allows querying for services “find all color displays with at least XGA resolution” slp://example.com/SrvRqst?public?type=printer SLP in multicast mode SLP in DA mode Need to discover services before getting to environment “is there a camera in the meeting room?” SLP extension: find remote DA via DNS SRV

51. May 23, 2005 Alcatel51 Internet Correspondent Node (CN) SIP UA SLP UA SIP SM Local Devices SLP SA SLP UA SIP SM SIP UA SLP DA Mobile Node (MN) SLP SIP RTP SIP UA Transcoder Session mobility

52. May 23, 2005 Alcatel52 Presence for spam prevention VoIP spam (“spit”) and IM spam (“spim”) likely to be more annoying than email spam Subscription to another person is indication of mutual trust other person allows me to see their status  trusts me Thus, use watcher list (who is watching me) as trust vector

53. May 23, 2005 Alcatel53 Conferencing issues

54. May 23, 2005 Alcatel54 Open issues for conferencing standardization Multi-device systems and session mobility Conference floor control  BFCP simple RPC-like protocol Centralized conference control (XCON WG) still struggling with control model set + get variables (~SNMP) RPC-like model (  SOAP, XML-RPC, NETCONF) send descriptions? forms (XForms?)?

55. May 23, 2005 Alcatel55 XCON System Logical XCON Server Floor Control Client TEMPLATE Of the SYSTEM: Pre-configured Initial/Default values Conf Event Notification Server Focus CPCP Client CCCP Client CPCP Server CCCP Server Call Signaling Client TEMPLATE Policy: Of TYPE RULES RESERVATION Policy: Of TYPE RULES CURRENT Policy: Of TYPE RULES RESERVATION Of the INSTANCE: Of TYPE CONFERENCE-INFO STATE Of the CURRENT INSTANCE: Of TYPE CONFERENCE-INFO Notification Client Floor Control Server SIP/ PSTN/ H.323 T.120/ Etc. CCCP CPCP SIP NOTIFY/ Etc. BFCP Logical XCON Client

56. May 23, 2005 Alcatel56 Open issues: application sharing Current: T.120 doesn’t integrate well with other conference control mechanisms hard to make work across platforms (fonts) ill-defined security mechanisms Current: web-based sharing hard to integrate with other media, control and record generally only works for Windows mostly limited to shared PowerPoint Current: vnc whole-screen sharing only can be coerced into conferencing, but doesn’t integrate well with control protocols

57. May 23, 2005 Alcatel57 IETF effort: standardized application sharing Remote access = application sharing Four components: window drawing ops  PNG keyboard input mouse input window operations (raise, lower, move) Uses RTP as transport synchronization with continuous media but typically, TCP allow multicast  large group sessions

58. May 23, 2005 Alcatel58 Conclusion Basic multimedia communication solutions available scalable, secure, good quality Media delivery  controlled interaction Binary presence  rich presence Presence as enabler of loosely-coupled advanced services location-based services serve as service script inputs trust indicator for spit/spim prevention Application sharing as missing link Harder to maintain focus in the IETF exhaustion, moving on to other things