IP telephony Evolution or revolution

Jan DamsgaardDept. of informatics

Copenhagen Business Schoolhttp://www.cbs.dk/staff/damsgaard/

IP telefoni J. Damsgaard, 2004 2

Agenda

IP telephony IP telephony as evolution IP telephony as revolution VoIP WLAN technology

IP telefoni J. Damsgaard, 2004 3

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 4

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 5

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 6

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 7

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 8

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 KaZaAhttp://www.skype.com/

IP telefoni J. Damsgaard, 2004 9

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 10

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 11

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 12

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 13

802.11x Standards

Standard 802.11 802.11a 802.11b 802.11g Available Date Jul-97 Sep-99 Sep-99 2002 End Frequency of Operation 2.4 GHz 5 GHz 2.4 GHz 2.4 GHz Total Bandwidth 83.5 MHz 300 MHz 83.5 MHz 83.5 MHz Modulation FHSS OFDM DSSS OFDM Non-overlapping Channels 3 12 3 3 Max. Data Rate 1.2 mbps 54 mbps 11 mbps 54 mbps Typical Range 50 feet 60 feet 100 feet 100 feet

IP telefoni J. Damsgaard, 2004 14

Clusters of public and private WLAN

WLAN broadband

Overlaping but closed WLANs

Overlaping open WLANs

IP telefoni J. Damsgaard, 2004 15

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.

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

IP telefoni J. Damsgaard, 2004 18

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