DCE Project Internet Telephony1 Internet Telephony %Introduction %What is it? %History %IP Telephony v. PSTN

DCE Project Internet Telephony2 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 %Telephone Network % reliable %Downtime measured in seconds per year %Regulation Data Packet SwitchedCircuit Switched

DCE Project Internet Telephony3 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 Internet Telephony4 IP Telephony Network Gatekeeper Gateway RTRT RTRT PSTN ISDN RTRT RTRT IP Network 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 Internet Telephony5 IP Telephony Services %Encompasses mphone-to-phone mphone-to-PC mPC-to-PC mfax-to-fax mvideo conferencing mdesktop collaboration %Software such as mMicrosoft NetMeeting mDeltaThree’s DotDialer mIDT’s Net2Phone

DCE Project Internet Telephony6 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 Internet Telephony7 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 Internet Telephony8 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 Internet Telephony9 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 mauthenticates users mencrypts payload mtracks who has changed packet %Incorporated in H.323 V2 via H.235 also called H Secure %Encryption Problems mPolitical/military issues (limits on keys etc) mHardware issues (processing power) %Dealing with security issues mUS Chamber of commerce announced automatic approvals for financial institutions mTherefore encryption more readily available??

DCE Project Internet Telephony10 Effect on the Traditional Communications Companies %Telecommunications or information service? %Telecommunications Act 1996 lpromote competition lfacilitate new telecommunications technologies

DCE Project Internet Telephony11 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 Internet Telephony12 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