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SIP Today: A Look at the Current State of the Standard
Amnon Gavish VP Business
DevelopmentRADVISION
AGENDA
SIP – The Emerging IP Communication Protocol
SIP Protocol Overview User Perspective - Applications and
Services Carrier perspective - Network aspects The Future
Just a moment, my laptop is ringing…
There’s a video call coming in on my desktop phone. Oops, my boss is trying to reach me on a cellular
POC call. Now who’s that instant message from? Oh, I hope that incoming file is the report I’ve been
waiting for. My messenger shows an incoming voice call on my
laptop. So many calls, over so many devices over so many
networks…
Wonder how it works?
Introducing the signaling protocol SIP
SIP = Session Initiation Protocol Signaling protocol for initiating, modifying, and
terminating interactive sessions A session can be voice, video, data or any
combination tied together by SIP. SIP enables any kind of communication everywhere at
any time. SIP enables new services in parallel with old services:
Presence, IM, Click to Talk….
SIP is the glue for Convergence! SIP is the NGN service enabler…
Where is SIP used?
Soft switchEverywhere!
SIP – The emerging IP communication protocol
The communication world is experiencing a revolution! Users want to communicate everywhere, in many ways,
and anytime. On the road, at home, at office… Talking, seeing, chatting, gaming, data transferring, and
everything together. While working, while on vacation, while traveling...
This means: Combining internet, cellular, wireless, and fixed networks
services. Moving to packet networks.
SIP is the glue for all this….
SIP – A little history 1996: started at Columbia University, submitted to the
Internet Engineering Task Force (IETF) March 1999: IETF RFC 2543 Sep. 1999: SIP Working Group is formed at the IETF 1999-2001: Several updates of RFC 2543 are released July 2000: Draft standard version of SIP submitted March 2001: SIP Working Group split into two groups
due to significant increase in SIP-related activity June 2002: RFC 3261 - The basis for today’s SIP
SIP has been adopted by various standards bodies
SIP adopted by different Consortia GSM/3GPP, CDMA/3GPP2 – SIP in 3G cellular networks CableLabs – Distributed Call State (DCS) specification International Softswitch Consortium – SIP as inter-
softswitch protocol (SIP-T) SUN/JAIN – Standard JAVA API for SIP
Other standards bodies involved in SIP International Telecommunication Union (ITU) International Multimedia Telecommunications
Consortium (IMTC)
What makes SIP protocol so popular? Uses proven Internet methods like HTTP/SMTP Integrates with Internet services
Instant messaging, presence, and more…
Flexibility Easily adopted for new services e.g. video, gaming…
Scalability SIP routing, makes it scalable by using a decentralized
architecture
Readability Developers like it ….
SIP Overview
SIP Operation
Registrar
User Agent 1
Location service
User Agent 2
Proxy
Redirect Server
SIP
Req
ues
t
SIP RequestSIP Request
read
update
REG
ISTE
R
SIP Philosophy Reuse Internet proven, rich set of concepts
Internet addressing and locating mechanisms Internet routing Internet protocols (HTTP, SMTP…) Advanced security methods Make no assumptions about the underlying packet
network transmission protocol (TCP, UDP…)
SIP provides building blocks for sessions control SIP can be read by humans; makes it more
friendly to understand
IETF SIP working groups SIP standardization working groups
SIP – Session initiation protocol SIPPING - Session Initiation Proposal Investigation SIMPLE - SIP for Instant Messaging and Presence
Leveraging Extensions IPTEL – IP telephony
Working groups with indirect connections to SIP AVT – Audio Video Telephony ENUM - Telephone Number Mapping Behave - Behavior Engineering for Hindrance
Avoidance XCON - Centralized Conferencing Many others…
Important Internet RFCs concerning SIP RFC3261: Session Initiation Protocol RFC3262: Reliability of Provisional Responses in SIP RFC3263: SIP: Locating SIP Servers RFC3264: An Offer/Answer Model with the Session Description Protocol RFC3265: Session Initiation Protocol (SIP)-Specific Event Notification RFC3892: The Session Initiation Protocol (SIP) Referred-By Mechanism RFC3891: The Session Initiation Protocol (SIP) Replaces Header RFC3856: A Presence Event Package for the Session Initiation Protocol
(SIP) RFC3857: A Watcher Information Event Template-Package for the
Session Initiation Protocol (SIP) RFC3824: Using E.164 numbers with the Session Initiation Protocol (SIP) RFC3764: ENUM service registration for Session Initiation Protocol (SIP)
Addresses-of-Record
Important Internet drafts relating to SIP
3rd-Generation Partnership Project (3GPP) Release 5 requirements for Session Initiation Protocol (SIP)
Connection reuse The Stream Control Transmission Protocol as a
Transport for for the Session Initiation Protocol Session Initiation Protocol Call Control -
Conferencing for User Agents Session timers Emergency Services for Internet Telephony systems
User Perspective - Applications and Services
SIP applications – practically everywhere…
Desktop IP phones Soft phones
PC Laptop Palm
Cellular phones Instant messaging user agents Presence user agents Streaming clients: IP radio
Carrier Perspective - Network Aspects
SIP network elements SIP Servers
Soft switches Proxy Redirect Registrar B2BUA Events and Presence IM
Application Servers ACD, IP Centrex…
Media Servers MCU, streaming servers, announcement servers
SIP usage in all networks Cellular/wireless
IMS - the new cellular core is SIP based Cellular endpoints use SIP for advanced features
(POC…) Endpoints and access servers over wireless networks
Fixed telephony Softswitches Gateways
Cable networks SIP infrastructure in packet cable networks
Internet Click to Talk Net2Phone
SIP Future
The future
Cellular networks are going to be SIP end-to-end
Fixed telephony networks are going to be SIP end-to-end
Internet telephony services will be SIP-based Packet Cables will use SIP in its backbone SIP will be used for converged services on
Handheld devices SIP will enable Gaming applications
BUT, let us return to the present
Reality is not that simple…There are many challenges(The “S” is not for simple…)
Some gaps between theory and reality
Move from fixed to mobile Signaling bandwidth Support for more addresses Advanced directory services
SIP based systems starting to replace legacy systems Robustness and reliability Features and services Security
Working on embedded platforms Many operating systems (RTOS) Footprint Efficiency
Internetworking and cooperation with other standards Standard is dynamic and evolving
