IETF Session Initiation Protocol

Henning Schulzrinne

Columbia University

New York, NY

SIP Overview

• Lightweight signaling protocol– to be standardized within IETF MMUSIC

– invite to new and on-going conferences

– multicast and unicast (“telephony”)

– personal mobility

– call center: reach first, first all

– change and add media

– post dial delay: 1.5 RTT

– uses either UDP or TCP

SIP and H.323

SIP H.32360+ pages 200+ pages (without

ASN.1)multicast signaling -personal mobility, INservices

Not (yet)

any session description H.245 1 audio, videoSSL, HTTP security in progress

SIP addresses food chain

yellow pages “president of the United States”common names “Bill Clinton, Whitehouse”host-independent president@whitehouse.govhost-specific sip://bubba@oval.eop.gov

sip://+1-202-456-1111@netph.com

IP address 198.137.241.30

SIP protocol

• text based (~ HTTP)

• methodsINVITE call user

CONNECTED confirm connectionBYE tear down call

transfer callREGISTER sign up with serverUNREGISTER “leave” server

SIP operation in redirect mode

SIP operation in proxy mode

SIP for Intelligent Networks• IN services “inside” & “outside” network

• UPN: translation by redirect server

• call forwarding: proxy, end system

• call transfer: BYE

• distinctive ringing: end system

• 800#: charging responsibility of resource reservation

• call center (queueing, first available)

For more information...

• http://www.cs.columbia.edu/~hgs/sip• IETF MMUSIC mailing list:confctrl-request@isi.edu