VoIP Signaling Protocols Framework

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VoIP Signaling Protocols Framework

• N. Rajagopal,
• MindTree Consulting Pvt Ltd

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Agenda

• H.323
• MGCP/MeGaCo
• SIP
• Deployment scenarios in India
• Summary

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H.323 Family of protocols

• ITU Recommendation
• V1 approved in 1996, V2 in 1998
• Defines multimedia applications over packet based
  networks
• Originally developed for voice over LANs
• Widely deployed

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H.323 Protocol Stack

• Peer to Peer nature
• Family of protocols
• H.225.0 Call signaling
• H.225.0 RAS
• H.245 Conference control
• RTP/RTCP for transport

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H.323 Components
H.323 MCU
H.323 Gatekeeper
H.323 Terminal
LAN
H.323 Gateway
ISDN
PSTN
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MGCP

• Media Gateway Control Protocol
• Based on master slave architecture
• Call agent master
• Media gateways slave
• Call agent
• Setups the calls between end points
• Media gateways
• Does IP lt-gt voice media conversion

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MGCP Protocol stack

• RFC 2705
• Supports packages for different applications
• DTMF, Trunking
• IVR, Media Server
• Uses RTP/RTCP for transport
• Designed for TCP/IP network
• Text based messages

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MGCP Network architecture
Call Agent
Trunking Gateway
IP Network
Trunking Gateway
IP Network
Media Gateway
Analog Phones
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MeGaCo

• Media Gateway Control Protocol
• Similar to MGCP
• More complete
• Flexibility
• Extensibility
• Video support
• Other transport support
• ATM

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SIP

• Session Initiation Protocol (RFC 2543)
• Management of multimedia sessions
• Simple, easy protocol
• 6 messages to get started
• Uses RTP for media transport
• Lots of extensions being proposed
• Standards evolving
• Possibility of different services
• Good potential

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Comparison between Protocols
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Comparison between protocols (contd)
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Deployment Scenarios in India

• H.323
• LAN Telephony
• Inter office PSTN toll bypass
• Remote office connectivity
• IP Phones

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Deployment scenarios in India
Office 1
Office 2
IP Phone
Leased lines
IP Network
PC
Office 3
PC
IP Phone
PC
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Deployment scenarios in India

• SIP
• Experimental
• Promises are high
• Windows XP support ubiquitous
• Likely areas of usage
• Desktops
• LAN telephony

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Deployment scenarios in India

• SIP
• Services
• Presence, messaging
• Integrated services
• Productivity improvement

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Deployment scenarios in India

• SIP
• Call Centers

PC
Phone
PC with SIP
Call Desk
Call Desk
PC
Phone Cabling
Network Cabling
Network Cabling
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Deployment scenarios in India

• MGCP
• Cable telephony
• MTU telephony

TV
Set Top Box (Media Gateway)
Headend (CallAgent)
Ethernet
POTS
Home
Cable
PSTN
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Summary

• H.323, SIP, MGCP all have their space in 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

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References

• http//www.softswitch.org
• http//www.ietf.org
• http//www.sipcenter.org
• http//www.cs.columbia.edu/sip