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IP TELEPHONY Voice over IP (VoIP). What is IP Telephony?. Compression to less than 32Kbps. Transfers through Routers, LAN Switches etc, using their Protocols. VoIP Placement. Telephone Replacement IPHONE, Ethernet Phone Transmission Substitution Tie Line, Trunk, Loop
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What is IP Telephony? Compression to less than 32Kbps Transfers through Routers, LAN Switches etc, using their Protocols
VoIP Placement • Telephone Replacement • IPHONE, Ethernet Phone • Transmission Substitution • Tie Line, Trunk, Loop • Switching Alternatives • PBX, CO, CENTREX
“Convergence” • Adding Voice, Video, Fax to Data Network • Unified Messaging • Centralized Communication Services • Email, Telephony, Multi-media • Common Protocol (IP)
Voice To/From IP Voice Analog CODEC: Analog to Digital Compress Create Voice Datagram Add Header (RTP, UDP, IP, etc) Digital
Voice To/From IP Digital Process Header Re-sequence and Buffer Delay Decompress CODEC: Digital to Analog Analog Voice
Dedicated Point-to-point Short/Constant Delay No Retransmission Low Error Tolerance Direct Pass Through Mainly connectionless Variable Delay Packet Loss Retransmission Uses protocols Traditional Network Characteristics Voice Data
Packet Network Technologies Same Components Different Performance An Intranet • Routing (TCP/IP) • Frame Relay • ATM • MPLS • Routing (TCP/IP) • Frame Relay • ATM • MPLS
Voice Over IP Networks VPN An Intranet • Subscribed • Environment • No Control except SLA • No Guarantees • Controlled • Environment • Performance Objectives • Designed to perform VPN: Virtual Private Networks
Compression Reduced bps vs. Quality Silence Suppression Assumptions Signaling Functions Speed Echo Control Local Quality of Service (QoS) Toll quality Voice Enhancements Directory services Feature: CLID, Call waiting Voice Over IP Requirements
IP PBX (LAN PBX) LAN PHONES GATEKEEPER: VIRTUAL PBX (SERVER BASED PBX) GATEWAY: EXTERNAL ACCESS CONNECTOR MCU: MULTIPOINT CONTROL UNIT (Conf. Call, 3 or more units)
Technical Issues • 64 Kbps or Compressed Voice • Standard or Proprietary • Network Size • Cable Distance (100m) • Operation Through LAN Switches • VoLAN or VoIP over LAN/WAN • Desktop Requirements • Global VoIP Standards
Voice Over IP Building Blocks Voice IP Protocol Network Regulatory Protocol Standards Performance Stanndards Standard Jitter Speech Coding IP Delay Access UDP Fees Call Control congestion TCP Separation SIP Network Payments RTP packetiza- tion Interface RTCP
H.323 Protocol Stack* Call Control Audio Video A/V Control Data G.7xx H.26x H.225 SIP H.245 T.120 RTCP RAS Q.931 RTP TCP UDP IP *SIP – Session Initiation Protocol is an alternative to H.323