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IP telephony Evolution or revolution Jan Damsgaard Dept. of informatics Copenhagen Business School http://www.cbs.dk/staff/damsgaard/ Agenda IP telephony IP telephony as evolution IP telephony as revolution VoIP WLAN technology IP telefoni J. Damsgaard, 2004 2 IP Telephony Circuit switched Vs. Packet switched IPv4 og IPv6 – Address space from 232 to 2128 – Or one address per square inch on earth Kilde: www.pcworld.dk IP telefoni J. Damsgaard, 2004 3 Soft Vs Hard IP telephony Hard IP – Box inserted between ordinary phone and broadband Internet connection (adsl or cable modem) – Stationary use – easy move of box – Maturing of existing technology. You can call everyone Soft IP – Software application that is installed on the computer which has to be running and connected to the Internet – Mobile use – wireless access – You can all all other users running the same program and if you kow their alias. IP telefoni J. Damsgaard, 2004 4 IP telephony as evolution Automation of existing services Usually it is the teleoperator that installes and operates hard IP telephony – Drives prices down faster The existing fixed net is used as analogy and IP telephony does not affect the provision of other services IP telefoni J. Damsgaard, 2004 5 IP telephony as evolution All communication through the same net – Integration of data, sound and images Relocation – – – – becomes easy From place to place (net-plug) Wireless phones Globally But also from work to home Voicemail can be sent as attachment to email IP telefoni J. Damsgaard, 2004 6 IP telephony as revolution Here is a radical departure in the provision of services and the way it is priced The computer is used as a phone – With speakers and a microphone The Internet is used as medium – VoDSL (Voice over Digital Subscriber Line) – QoS a problem? (64 kbit/s) IP telefoni J. Damsgaard, 2004 7 Skype Skype is a piece of software that enables free telephone conversations from anywhere to anywhere – You do not pay per minute or more the longer distance – Teleoperator cut out of the loop Skype uses P2P (peer-to-peer) technology where an Instant messenger is combined with telephony Skype is created by the people behind KaZaA http://www.skype.com/ IP telefoni J. Damsgaard, 2004 8 The best from both worlds RTX has developed a wireless IP telephone Contrary to most other phones the new RTX phone has two jacks. One for the Internet and one for the PSTN. I.e. you only need one phone and it bridges the two worlds The wirless RTX phone can run a Skype Client The wireless phone connects through the WLAN Voila – a VoFi (802.11x-enabled VoIP) telephone Kilde: www.computerworld.dk IP telefoni J. Damsgaard, 2004 9 And there is more coming Motorola and NEC collaborate to develop an IP telephone that can roam from a WiFi hotspot to the GSM network without loosing the IP address Motorola’s components include a WiFi enabled mobile phone and a "mobility manager” that manages the hand over between a WLAN and the public mobile network IP telefoni J. Damsgaard, 2004 10 And it does not stop Community based WLAN VoIP Users shift from being passive consumers of telecommucation services they become active providers of telecommuncation services Imagine that your WLAN together with your neighbour’s WLAN become small pieces of a giant telecommunication infrastructure that in comparison to 3G is much faster Teleoperators become bit pipes IP telefoni J. Damsgaard, 2004 11 We have never been mobile Only serial stationary – We move in steps and therefore we do not need broadband while in transition (exceeding 64 kb/s) – WLAN at work, in the home, at the gasoline station at the mall But not between them This is good news for WLAN and bad news for UMTS IP telefoni J. Damsgaard, 2004 12 802.11x Standards Standard Available Date Frequency of Operation Total Bandwidth Modulation Non-overlapping Channels Max. Data Rate Typical Range IP telefoni 802.11 Jul-97 2.4 GHz 83.5 MHz FHSS 3 1.2 mbps 50 feet 802.11a Sep-99 5 GHz 300 MHz OFDM 12 54 mbps 60 feet J. Damsgaard, 2004 802.11b Sep-99 2.4 GHz 83.5 MHz DSSS 3 11 mbps 100 feet 802.11g 2002 End 2.4 GHz 83.5 MHz OFDM 3 54 mbps 100 feet 13 WLAN broadband Clusters of public and private WLAN Overlaping but closed WLANs IP telefoni J. Damsgaard, 2004 Overlaping open WLANs 14 Tragedy of the commons Hardin (1968) describes it as a situation in which too many actors have privileges to consume a common resource leading to its overuse and eventually collapse. The tragedy of the commons has been described as a social trap because behavior that gratifies the individual in the short-term has long-term collective costs For example, every fisherman has the incentive to maximize her current harvest, while the carrying capacity of the fish stock is limited. Therefore, if fishermen combined harvest at a higher rate than the fish can reproduce, the resource will soon be exhausted This behavioral pattern locks in the individual in a scheme that is destructive for the common resource. In the long term the individuals therefore become victim of their collective actions. Hardin, Garrett (1968). “The Tragedy of the Commons” Science, December, 13. 1243-1248. IP telefoni J. Damsgaard, 2004 15 Causes and Counter Measures Counter Measures Pasture Challenges WBN Challenges Open Commons Closed Commons Over-grazing Adding more cows Adding more devices than own fair share Nothing can be done Control number of devices Stealing Taking others cows Taking over the devices of other for own needs Safeguard own devices Warn/disable offenders Poaching Killing others cows Disabling operations of other members’ devices Protect own devices Police the network and punish offenders Tainting Allowing sick cows in commons Affecting others’ devices through non-carefulness Vaccinate own devices Quarantine infected devices Contamination Reducing the amount of grass Maliciously reducing the bandwidth Nothing can be done Disable contaminating devices or members So what Moores law – Double the capacity every 18 months – Makes the tragedy of the commons to a purely theoretical discussion Napster and KaZaA – Supercows that eat any available piece of grass Year of Introduction Transistors 4004 1971 2,250 8008 1972 2,500 8080 1974 5,000 8086 1978 29,000 286 1982 120,000 Intel386™ processor 1985 275,000 Intel486™ processor 1989 1,180,000 Intel® Pentium® processor 1993 3,100,000 Intel® Pentium® II processor 1997 7,500,000 Intel® Pentium® III processor 1999 24,000,000 Intel® Pentium® 4 processor 2000 42,000,000 Intel® Itanium® processor 2002 220,000,000 Intel® Itanium® 2 processor 2003 410,000,000 Source: http://www.intel.com/research/silicon/mooreslaw.htm Conclusions IP telephony is the future – Either as evolution or revolution Convergence of GSM/GPRS/UMTS/WiFi/UWB/BT into one mobile unit (integrates PDA/Telephone/Data etc.) Dynamic shift between available resources – Maybe even auction IP telefoni J. 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