International Telecommunication Union VoIP Signaling Protocols Framework N. Rajagopal, MindTree Consulting Pvt Ltd ITU-T and ITU-D Workshop Bangalore (India), 30-31 August 2001 Agenda o o o o o 31.05.2016 H.323 MGCP/MeGaCo SIP Deployment scenarios in India Summary ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 2 H.323 Family of protocols o ITU Recommendation • V1 approved in 1996, V2 in 1998 o Defines multimedia applications over packet based networks o Originally developed for voice over LANs o Widely deployed 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 3 H.323 Protocol Stack o Peer to Peer nature o Family of protocols o H.225.0: Call signaling o H.225.0 RAS o H.245 Conference control o RTP/RTCP for transport 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 4 H.323 Components H.323 MCU H.323 Gatekeeper H.323 Terminal LAN H.323 Gateway PSTN 31.05.2016 ISDN ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 5 MGCP o o o o o Media Gateway Control Protocol Based on master –slave architecture “Call agent” – master “Media gateways” – slave Call agent • Setups the calls between end points o Media gateways • Does IP <-> voice media conversion 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 6 MGCP Protocol stack o RFC 2705 o Supports “packages” for different applications • DTMF, Trunking • IVR, Media Server o Uses RTP/RTCP for transport o Designed for TCP/IP network o Text based messages 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 7 MGCP Network architecture Call Agent Trunking Gateway IP Network Network IP Trunking Gateway Media Gateway Analog Phones 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 8 MeGaCo o Media Gateway Control Protocol o Similar to MGCP o More complete • Flexibility • Extensibility o Video support o Other transport support • ATM 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 9 SIP o Session Initiation Protocol (RFC 2543) o Management of multimedia sessions o Simple, easy protocol • 6 messages to get started o Uses RTP for media transport o Lots of extensions being proposed o Standards evolving o Possibility of different services o Good potential 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 10 Comparison between Protocols 31.05.2016 Protocol-> H.323 MGCP/MeGa Co SIP Purpose Multimedia conferencing; Media gateway control Multimedia conferencing Defined by ITU-T IETF IETF Complexity High (multiple protocols: H.225.0 for signaling, H.225 RAS for GK communication, H.245 for call signaling Moderate Simple (6 messages) Endpoint requirements Intelligent Dumb (POTS will do) Intelligent PSTN connectivity thru Gateway Media Gateway + Signaling Gateway Outbound proxy ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 11 Comparison between protocols (cont’d) Number of messages H.323/100+ MGCP/~10 SIP/6 Type of messages Binary Text, readable Text, readable SDP SDP Media description 31.05.2016 Voice Transport RTP RTP RTP Signaling transport TCP UDP UDP/TCP Capabilities H.245 for capabilities exchange to support different transfers Limited SDP; limited abilities Extensibility Difficult Easy Easy Remarks Legacy; Need to support for today’s networks May get relegated to trunking after widespread deployment of SIP Likely Signaling protocol of future! ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 12 Deployment Scenarios in India o H.323 • LAN Telephony • Inter office PSTN toll bypass • Remote office connectivity • IP Phones 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 13 Deployment scenarios in India Office 1 Office 2 IP Network Leased lines IP Phone PC Office 3 PC 31.05.2016 IP Phone PC ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 14 Deployment scenarios in India o SIP • Experimental • Promises are high • Windows XP support – ubiquitous o Likely areas of usage • Desktops • LAN telephony 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 15 Deployment scenarios in India o SIP • Services • Presence, messaging • Integrated services • Productivity improvement 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 16 Deployment scenarios in India o SIP • Call Centers PC Phone Call Desk Network Cabling 31.05.2016 PC Phone Cabling PC with SIP Call Desk Network Cabling ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 17 Deployment scenarios in India o MGCP • Cable telephony • MTU telephony Headend (CallAgent) TV Set Top Box (Media Gateway) Ethernet POTS Home Cable PSTN 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 18 Summary o H.323, SIP, MGCP all have their space in o o o o 31.05.2016 VoIP space Likely coexistence “Softswitch architecture” to control the elements in VoIP network “Services” will be key differentiator for customer CLECs/new generation service providers likely to go for softswitch based solution ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 19 References o http://www.softswitch.org o http://www.ietf.org o http://www.sipcenter.org o http://www.cs.columbia.edu/sip 31.05.2016 ITU-T and ITU-D Workshop - Bangalore (India), 30-31 August 2001 20