Simple Universal

Call/Conference

Establishment Sequence -

SUCCESS

P. Cordell, BT Labs

Overview

u Purpose u Protocol requirements u Brief protocol description u Capability negotiation u Message encoding u Conclusion

Purpose

u Exchange ideas u Share our requirements

u Work in progress

A Single Protocol

u Easy to listen to u No protocol interworking issues u Uniform extension mechanism u Single initial point of contact ? May jump into SCCP, T.120 or H.323 later

Extensible Call Model

u Loose control u Tight control ? Membership kept in call control plane ? Close down phase ? Progress information for user and diagnostics

Extensible Features

u Supplementary services ? Transfer, Hold etc. u Authentication u Floor control u Java Applets

u Extension through standards bodies u Extension by proprietary (de-facto?) features

Universal Initiation

u Initiate real-time conversational streams u Initiate live ?broadcast? feeds u Initiate pre-stored server feeds ? Including answering machine functions etc.

Environment

u Interworking with POTS and H.320 u Third party call control ? Call centres ? Managed conferences

The Pro tocol

u He ll o - An n o u n c e p r e se n c e in c o n f er e n c e ? In cl ud es re pl y an d re pl y- a ck fi el d u Pr o g r e ss - I n d i c at e p r o g r e ss e n te r i n g c a ll u B y e - I n d i c at e l ea v i n g c o n f e r en c e u B y eB y e - Ac k n o wl e d g e en d p o in t l e av i n g u Fe at u r e - Ex t e n si b le f ea t u r e f r am e w o r k

u draft-cordell-success-00.txt.Z

Fea tur eM es s age

u Functionality supported by ?plug-ins? u Fe a tu re s re g is te rw ith c a ll c on tr o ll ay e r u C al lc o nt ro l ex c h an g es me ss a ge s u C he c k fo r re g ist e re d fe at u re o n me ss ag e reception

C apab ility Nego tiatio n

u Impor tantto allown ew,bet tercod ecsu Recom mend commo nbase set

?G.7 23-Goo dforslo wlinks? QCI FH.261 -Comp atiblew ithexisti ngs tan dards

u Negotiation prior to conference

Negot iationu CapabilitiesinHello messageu Messageindicatesstr eamsbeingsentu Allowsmultiplesetso fmediasomultiples treamsofsimilartyp ecanbenegotiatedu Candeterminecomm onreceivecapabilities

overtimeuReceiversmayhavet oswitchdecodersb asedonRTPheader

AligningwithSIPINVITE128.16.64.19/65729SIP/2.0From:mjh@isi.eduTo:*To:schooler@cs.caltech.eduReplyTo:pete@bt.comRespond-to:INIP4UDP239.128.16.254116Content-type:meta/sdpContent-Length:187

MessageEncodinguMessagedescriptionindependentoflineformatuOptionalfutureextensionsrequireshierarchyinmessagesuCommonformatallows?Easyunderstanding?Easydefinitionofnewstandards?Codere-use

EncodingSuggestionuASCIIlineformatuASN.1subsetmessagedescriptionINTEGEROCTETIA5StringBMPStringSTRINGSIZESEQUENCECHOICEBOOLEANNULLOPTIONALSETOFSEQUENCEOFuLineformat:x=y

EncodingExamplesuASN.1:sizeINTEGER(0..255),coded as:size=12uASN.1:linkSEQUENCE{addressIA5String(SIZE(0..255)),portINTEGER(0..65535)}coded as:link=(address=?bt.com?port=1200)

UseAbbreviationsuIf:link==laddress==aport==puMessagebecomes:l=(a=?bt.com?p=1200)

ConclusionuSingle extensible protocol requireduInterworking with existing networksrequireduNetworkservicesrequireduThird-partycontrolrequired