Voice and Data Integration over IP An analytical overview of voice-over-IP Prabhu Sivarja Wichita State University, Wichita, KS Spring 2003

Goal To define voice-over-IP To give a brief overview of this technology To enlighten and not confuse the listeners

Contents Introduction Traditional Voice Networks Voice-over-IP Networks Strategies regarding implementation

Introduction What is voice-over-IP? – The transmission of voice over IP networks in the form of packets. What are the benefits of voice-over-IP? – Cost Reduction – Voice and Data Integration – Bandwidth Efficiency – New Applications

Traditional Voice Networks

Voice-over-IP Networks

Standards in Voice-over-IP H.323 Session Initiation Protocol(SIP)

Components of H.323 Media Gateways Media Gatekeepers Multipoint Control Units (MCU) Protcols used

Components of H.323 Media Gateways – Hardware that acts an entry point for the voice into the IP cloud. Searches and maps phone numbers to IP addresses Connects to remote gateways Converts from Analog to digital Compresses voice

Components of H.323 Media Gate Keepers – Authority that manages the gateways Address Translation Admission Control Bandwidth Management Zone Management Call Management Multipoint Control Unit (MCU) – Conference calling support

Components of H.323 Protocols Used Data T.120 TCP Network Layer Data Link Layer UDP H Call Signaling H.245 Conference Control RTP/RTCPH RAS Control and Signaling Audio/ Video Registrati on Physical Layer

Steps involved in the transmission of voice packets over a H.323 network Discovering gate keeper by gateway Registering gateway with gatekeeper Gateway enters setup phase The capability exchange between gatekeeper and gateway The call is established between two gateways Transmission of voice packets between gateways Termination of logical connection

Session Initiation Protocol Application level protocol which manages voice communication Based on the client server approach Communicates by passing messages – Invite, Bye, Redirect, Acknowledge Shares similarities between SMTP Offers personal mobility

Steps involved in the transmission of voice packets over a SIP network

H.323 vs. SIP H.323 SIP Complex ProtocolComparatively Simpler Binary Representation of msgsText Representation of msgs Requires full backward compatibility Does not require full backward compatibility Not very modularVery modular Not very scalableVery scalable Complex signalingSimple signaling Large share of marketNot too large a share but backed by IETF Hundreds of elementsOnly 37 headers

Strategies regarding implementation Simple Toll Bypass – Used for small organizations – Minimal changes – No PSTN integration Total IP Telephony – Complete overhaul of the phone network – Traditional phones -> IP phones – LAN servers IP Enabled PBX – Intermediate solution. PBX is upgraded to talk to IP cloud

Conclusion Voice-over-IP has it advantages. – Economical – Efficient – Voice/Data Integration – New Services Best strategy is the IP enabled PBX (Intermediate approach) – Can be implemented on top of existing voice networks.

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