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Internet Telephony

Internet Telephony. Introduction What is it? History IP Telephony v. PSTN. Calls broken to pieces and sent to destination Better use of network capacity Data Network 80% reliable Downtime is 4 hours per month (Data Communications). Dedicated circuit for each call

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Internet Telephony

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  1. Internet Telephony • Introduction • What is it? • History • IP Telephony v. PSTN DCE Project 1999 - Internet Telephony

  2. Calls broken to pieces and sent to destination Better use of network capacity Data Network 80% reliable Downtime is 4 hours per month (Data Communications) Dedicated circuit for each call Telephone Network 99.999% reliable Downtime measured in seconds per year Regulation IP Telephony v PSTN Data Packet Switched Circuit Switched DCE Project 1999 - Internet Telephony

  3. Voice Gateways • Physical interface • Placed between PSTN and IP Network • Handles • signaling to and from telephone network • reception of telephone numbers • conversion of tel nos to IP addresses • voice processing • reception of voice signal • compression(to reduce bandwidth and delay impact from Network) and packetization • echo cancellation • silence suppression • No of gateways crucial - around 500 in existence DCE Project 1999 - Internet Telephony

  4. RT RT RT RT IP Telephony Network Gatekeeper IP Network ISDN PSTN PSTN Gateway Gateway Gateway Gateway : Bridge between PSTN & IP Networks Gatekeeper : Admission control for network Bandwidth control and management Address translation (E.164 <-> IP address) Call Management DCE Project 1999 - Internet Telephony

  5. IP Telephony Services • Encompasses • phone-to-phone • phone-to-PC • PC-to-PC • fax-to-fax • video conferencing • desktop collaboration • Software such as • Microsoft NetMeeting • DeltaThree’s DotDialer • IDT’s Net2Phone DCE Project 1999 - Internet Telephony

  6. Standards • Why do we need them? • The benefits of standardisation • Interoperability • billing, settlement and reconciliation • uniformity for carriers • marketability • Currently • no standards for signaling • no standard agreement on accounting records or billing • These issues being handled through maturing standards such as ITU’s • H.323 • Tiphon DCE Project 1999 - Internet Telephony

  7. H.323-The Vendors Choice? • H.323 recommends G.723 • compresses voice to 5.3 or 6.3 kbit/s • Some using GSM algorithm • compresses to 13.3 kbit/s, appears to provide superior quality to G.723 • Tiphon • based on H.323 • specifies network architecture, numbering, supplementary services integration DCE Project 1999 - Internet Telephony

  8. Security • Initially somewhat overlooked, now being raised by carriers and business users • Security Issues • User and data authentication • Data privacy (integrity, confidentiality) • Access control • Policy management • Security Measures • Encryption • SSL (secure sockets layer) • TLS (transport layer security) • Tunnelling • Layer 2 Tunnelling Protocol (L2TP) • establish a secure tunnel between gateways or gatekeepers DCE Project 1999 - Internet Telephony

  9. Encryption • SSL, TLS on transport level, suitable for Gatekeeper-to-gatekeeper, but not if unreliable, connectionless UDP transports the voice • IETF IPsec working group describes security architecture for IP protocol that makes it suitable for secure VPN • authenticates users • encrypts payload • tracks who has changed packet • Incorporated in H.323 V2 via H.235 also called H Secure • Encryption Problems • Political/military issues (limits on keys etc) • Hardware issues (processing power) • Dealing with security issues • US Chamber of commerce announced automatic approvals for financial institutions • Therefore encryption more readily available?? DCE Project 1999 - Internet Telephony

  10. Effect on the Traditional Communications Companies • Telecommunications or information service? • Telecommunications Act 1996 • promote competition • facilitate new telecommunications technologies DCE Project 1999 - Internet Telephony

  11. Economics • Cost savings dependent on the provider and location • Calls between London and Tokyo around 30 cents per minute ($1 per minute for POTS) DCE Project 1999 - Internet Telephony

  12. The Future • Market predicted to grow to $560 million by end of 1999 • By 2002, 3% of US long-distance traffic, 5% of European long-distance traffic, 14% of US international traffic and 11% of European international traffic • Not economic but service benefit • Used with video and data sharing for multi-media communications DCE Project 1999 - Internet Telephony

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