SIP for IP Communications

2. SIP for IP Communications Jonathan Rosenberg Chief Scientist

3. IP Communications • “Communications” consists of more than just voice • video • IM • presence • wireless • Presence and IM are of particular interest • Question for discussion: • What is SIP’s role in presence and IM?

4. Also Known as Buddy Lists Indicates Online/Offline Status Used Largely to Enable IM Users Subscribe to “Friends” List When User is Online Click to send instant message Initiate voice chat (newer) When Friends Log On/Off, Notifications are Sent User Status Can Sometimes Be Indicated Busy, not at my desk Subscriber Presence Server Subscriber Publisher Subscriber Notify Subscribe Publish Presence Today

5. Presence Today cont. • No Standard for IM or Presence • Many Players (i.e., AOL, Yahoo and Tribal Voice) • Each with its own, non-interoperable system • User’s Experience is Limited • Metcalfe’s Law • Running many different applications • IETF IMPP Group Tasked to Develop a Standard Solution • Proposals Solicited for a Complete Solution at April 2000 Meeting • A SIP Solution was Submitted • Co-authors from dynamicsoft, Microsoft, Cisco and Columbia University

6. Subscription Definition: to subscribe to some entity Requires massive scalability Distributed subscription state Lightweight transactions Authentication of subscribers Ability to convey complex subscription rules Routing and namespace partitioning Components of a Presence Solution

7. Publication Enables a user to send information to server for distribution Must be possible to have multiple entities publish for a single address My cell phone My IM client Describes communications means, state, capabilities and characteristics Components of a Presence Solution cont.

8. Notification Rapid delivery of published data to subscribers Makes use of distributed subscription state Highly scalable Presence data changes often Many subscribers Must be able to convey a variety of presence data formats Components of a Presence Solution cont.

9. Network Awareness of Presence State SIP for call routing Presence for distribution to subscribers Real-Time Delivery Forwarding to Server Responsible for a Specific User Scalability Session Initiation and Presence/IM Share Requirements

10. Security Privacy Access controls Authentication Carriage of MIME Data Extensibility Session Initiation and Presence/IM Share Requirements cont.

11. REGISTER is a Publication Message for Locations Allows for SIP and Other URL Types Multiple Entities Can Publish for the Same Address SIP Caller Preferences Extension Allows for Attributes for Locations Mobile, landline Home, business Preferences Audio,video - MIME capability Registrar Registrar Client Client Client SIP Already Provides Publication Capability

12. New Entity: Presence Agent Purely logical entity Knows presence state of user Receives SUBSCRIBE requests Generates NOTIFY requests Co-located with proxy/registrar or User Agent Basic Operation Subscriber send SUBSCRIBE Routed to PA using normal SIP PA authorizes subscriber Acceptance contains presence state NOTIFY sent when state changes Routed using SIP Record-Route Subscriber SUBSCRIBE Proxy NOTIFY Presence Agent + Proxy/Registrar = Presence Server REGISTER Presentity SIP Extension for Presence

13. Features of SIP For Presence Extension • End Users Can Perform Notifications • Scalability • Presence Agent Function Can Migrate • Network provides service when user is offline • When user is online, subscriptions migrate to user • Offline Subscriptions Handled • Presence server always asks user if a subscription should be accepted

14. Features of SIP For Presence Extension cont. • Multiple Entities Can Generate Presence Information for One Presentity • Mobile phone, PDA, laptop and desktop PC • Multiple Presence Clients Can Be Online at Once • Traditional SIP Proxies Route SUBSCRIBE and NOTIFY • Presence Data is Orthogonal

15. SIP Extension for Instant Messaging • Operation of Extension • Messages carried in SIP messages • New method - MESSAGE • Routed to recipient using normal SIP techniques • Simple extension • Features • Associates an IM with an existing call • Any MIME data can be sent • TCP for large messages • Routed by existing proxies and registrars • Possible to have a different client for IM and communications

16. Unifies Major Communications Services Voice/video IM Presence Shared Databases Shared Proxies Shared Servers Advantages of Using SIP for Presence and IM

17. Reduces Management Costs One infrastructure instead of two One NOC instead of two One set of managers instead of two Enables New Combined Services Combined services integrate voice, video, IM, presence, web amd email These new services will be a “killer app” for communications on the Internet Delivery of combined services is greatly simplified by alignment of presence and communication signaling protocols Advantages of Using SIP For Presence and IM

18. Uses Geographic Locale as Presence Component Mobile phone site location GPS Service Definition Turn on mobile phone in car As you drive, application server monitors location As you approach traffic, service will call you Voice response system reads out alternate route New Service Example: Traffic Jam Alerts NOTIFY Application Server INVITE Presence Server REGISTER

19. Problem: Difficult to juggle busy people’s schedules to set up audio conference calls Solution: use presence to set up the call when everyone is available Procedure: Enter email addresses into a web form (1) Application subscribes to users (2) When all are online, application calls each participant, calls a conference bridge, connects them together New Service Example: Auto Conference Calls Conference Server AS Presence Server Presence HTTP SIP Calls

20. Information Resource • Jonathan Rosenberg • jdrosen@dynamicsoft.com • +1 973.952.5000