k'k'chaistaffs'ac'uk

1
MCCS Voice over IP

• What we will look at
• What it is
• Who is expecting to use this technology
• What are the concerns with the use of this
  technology

2
MCCS - VoIP

• Voice over Internet Protocol (VoIP)
• This technology allows for the movement of voice
  data across a computer network
• Codec converts analogue voice signals into
  digital representations was paramount
• This then allowed this digital data to be
  transferred across the networks

3
MCCS - VoIP

• Using the Internet will allow for cheap
  international calls
• All that is needed is a connection to the network
  with sufficient
• Latency
• Throughput
• Future proof technology
• Only the protocol will need updating
• These are software based and relatively easy to
  update

4
MCCS VoIP Steps

• Steps for VoIP
• Convert the Analogue voice to digital data (ADC)
• Compress the digital ready for transport (CODEC)
• A number of different codecs are used depending
  on the scenario
• G.711
• G.722
• G.723
• List of which software supports which standard
• http//compare.ozvoip.com/codecsupport.php
• Place packets on the network for transport
• We need a signaling protocol to call users. E.g.
  H323 or SIP.
• Receiver converts packet back to analogue
  information to listen to

5
MCCS - VoIP

• Network
• Voice data can be transferred across normal
  business network connections
• This means that investment in computer network
  can be expanded upon
• Voice calls being put onto the same network
• This does bring issues in its own right
• About how to deliver packets in a timely manner

6
MCCS - VoIP

• Timely delivery
• Two factors will effect this
• The majority of business networks are Ethernet
• IPv4 version does not support any sort of Quality
  of service
• Both of the technologies used in the majority of
  networks are Best Effort
• This indicates that the network will do its best
  to deliver as quickly as possible
• It is NOT guaranteed
• This is a problem for phone conversations where
  delivery of data in a timely manner is essential
• VOIP must as far as possible at least provide the
  same service as the PSTN

7
MCCS - VoIP

• Delays
• Official figures are given by the ITU-T
• These figures are intended as a guideline for
  usability of telecommunications
• Including VOIP
• 0 to 150ms
• Acceptable for most user applications
• 150 to 400ms
• Acceptable delay for usage within international
  telecommunications
• gt 400ms
• Unacceptable for general use. Although it is
  recognised that there will be situations where
  this guideline will be exceeded.

8
MCCS - VoIP

• Networks
• With proper planning there will not be a concern
  for VOIP
• But it does require consideration in the network
  plan
• Rather than just adding it to the current
  infrastructure
• New and separate network can be allocated for the
  VOIP traffic
• This can be used as a backup anyway to the main
  network

9
MCCS - VoIP

• Transporting voice data
• Commonly for data traffic IP is used in
  conjunction with TCP
• In VoIP networks though guaranteed delivery is
  not a requirement
• A few lost packets is fine, with the human ear
  being able to interpret missing information
• A paper by Intel discusses a maximum packet loss
  of 1 before the end user can hear the loss
• http//www.intel.com/network/csp/pdf/8539.pdf
• VoIP packets are transported with a combination
  of UDP and RTP

10
MCCS UDP

• User Datagram Protocol (UDP)
• Intended for speed rather than reliability
• Widely used were it is more important that the
  packets arrive quickly i.e. audio, video stream,
  online games
• Connectionless service
• Small header
• No support Packet ordering
• No support for packet delays
• On its own UDP would be useless for VoIP
• No packet ordering would cause voice signals to
  be corrupted
• Delays
• They can cause echoes in the conversation which
  would ruin the quality of the conversation

11
MCCS RTP

• Real Time Transport Protocol (RTP)
• The RTP is used to give some level of reliability
  to UDP
• Application layer protocol
• Allows for sequencing in a packet reordering
• Supports time stamping of the packets
• It does not give the full functionality of TCP as
  this is not required
• Widely used for streaming applications and
  Multimedia

12
MCCS Signalling

• The majority of VoIP installations use H.323
  standards
• Alternative is Session Initiation Protocol (SIP)
• These are a set of standards which are used to
  agree how to transfer multimedia (including VOIP)
  data across a IP based network

13
MCCS H.323

• H.323
• These standards were not developed for VOIP, they
  were intended for Multimedia across a network
• Microsoft Net Meeting and MSN Messenger use these
  standards
• H.323 allows communications within the IP
  networks and communications with the PSTN
• Allows signal communications across all of the
  elements which make up the VOIP network
• Link to a website that details to
  http//www.packetizer.com/voip/h323/standards.html
  

14
MCCS SIP

• Session Initiation Protocol
• This is designed as a lightweight peer to peer
  communications method for the setting up of
  communications
• It is not intended as a transport method
• The components of SIP are
• Proxy
• This server forwards the communications to the
  user agent
• If two organisations link then the proxy can be
  configured for the communications automatically
• Registrar
• This server records your location and how to
  contact you
• Redirect Server
• This server will redirect communications to your
  current location if you have moved
• As in you are working at home today
• User Agent
• This is the application which is requesting the
  service or the server which is responding
• Communications are peer to peer
• If connecting to the PSTN this would be a user
  agent

15
MCCS VoIP PSTN

• VoIP
• So far in main we have discussed communicating
  VOIP -gt VOIP
• If this was the extent of its use it would not be
  useful to corporations
• VoIP can be fully integrated into PSTN networks
• VoIP -gt PSTN
• PSTN -gt VoIP
• Gateways allow the two differing networks to
  communicate

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MCCS Connecting to PSTN

• VoIP
• Unless the devices can connect to the PSTN they
  will remain a fringe use
• The standards allow for normal type phones to be
  attached
• Businesses are now recognising the benefits
• Especially those who have invested heavily in the
  networks
• Members of the public are using this technology
  increasingly
• Cheap international calls
• Other service provided like, Video, text

17
MCCS - VoIP

• British Telecom (BT)
• Has embraced the development of VOIP
• All of the call centres for BT are using VOIP
• http//www.computerweekly.com/Article135541.htm
• They have also set up a voip service with Yahoo
• This service will allow free calls between two
  PCs
• The users can also make cheap calls to
  traditional phones
• http//www.pcw.co.uk/news/1156674
• Other VOIP providers are coming online
• news.bbc.co.uk/1/hi/technology/4254399.stm

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MCCS - VoIP

• The most widely known of the providers is Skype
• Proving VOIP to computer users
• Also allowing text and video calls as well
• Allowing the integration into the PSTN network
• September 2005, EBay purchased Skype for 2.6
  Billion
• http//news.bbc.co.uk/1/hi/business/4237338.stm
• The intention was to link the Ebay auctions with
  Skype, which can be seen with some operators on
  there adverts

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MCCS - VoIP

• Microsoft is also looking at this market
• In August 2005 they purchase the VOIP company
  Teleco
• http//www.teleclick.ca/2005/08/microsoft-buys-voi
  p-startup/
• The amount of money is still undisclosed
• Some of the discussion is for Microsoft Messenger
  to be linked to provide localised telephone
  services
• Phone my local flower shop
• Call Microsoft support if a problem can not be
  resolved
• In December 2006 Microsoft have announced the
  Office Communication server beta
• http//www.microsoft.com/presspass/press/2006/dec0
  6/12-11PrivateBetaPR.mspx
• Based around the use of SIP
• http//www.voip-news.com/feature/microsoft-pbx-str
  ategy-011207/

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MCCS - VoIP

• The companies are getting involved due to the
  future potential earnings
• To be in the market in the beginning gives a
  large advantage when it starts to be widely
  accepted
• As network connections develop higher throughput
  with QOS, users will want additional services to
  use these
• Forecasts in the market of revenues of 1.3
  Billion a year by 2009 (2 years away)
• http//www.internetnews.com/infra/article.php/3565
  901
• They discuss the essential element of wireless
  technology being used to communicate with
  computer
• i.e. a Bluetooth phone attaching to the computer,
  where the packets are then transferred rather
  than the headset currently used

21
MCCS - VoIP

• Regulations
• PSTN operators have a set of services they MUST
  provide due to regulation
• The consideration is should this be the same for
  VOIP ?
• Voice services are regulated
• IP services are not
• This is currently being investigated in the UK by
  OFCOM
• Findings from November 2004
• Can be found here www.ofcom.org.uk/consult/condocs
  /new_voice/anew_voice/?a87101
• In November 2006 OFCOM agreed that VOIP numbers
  can have the prefix of 056, most operators though
  will still use geographic numbers such as 0161
  Manchester
• http//www.ofcom.org.uk/media/mofaq/telecoms/voip_
  faq/

22
MCCS - VoIP

• Regulations
• Initial considerations
• VOIP operators should not required to offer all
  of the services PSTN operators do
• Although desirable the 999/911/112 service does
  not have to be offered
• Although the customers must be informed of this
• This will also be reviewed as the market develops
  to possible make the operators support some sort
  of 999 service

23
MCCS - VoIP

• Why is a 999 call such a problem in VOIP ?
• In traditional the PSTN the current position of
  you phone is known
• You are physically connected to the network at
  that point
• Mobile phone operators
• Can find your location via the base station you
  are attached to
• Using multiple signals your exact location can be
  discovered
• This means if you phone 999 but you do not know
  your location the operator can find it for you
• In VOIP this is not correct, you are just a IP
  address
• You may be connecting into the exchange in
  London, but physically located in Manchester

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MCCS VOIP Future

• In the US by the 14th of May
• All VOIP operators must allow the capability for
  court appointed agencies to listen to
  communications
• http//www.voipsa.org/blog/2006/06/13/voip-provide
  rs-must-adhere-to-calea-by-next-may-14/
• This would make VOIP similar to normal PSTN
  operators
• The EU has is also looking at the same law
• http//technology.guardian.co.uk/weekly/story/0,,1
  830460,00.html
• By 2010 EU data retention laws require operators
  to record the details of calls made or attempted
• Directive 2006/24/EC
• This is just the fact that a call was made
  between point a and B not the contents of the
  call
• http//europa.eu.int/eur-lex/lex/LexUriServ/site/e
  n/oj/2006/l_105/l_10520060413en00540063.pdf

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MCCS Conclusion VOIP Future

• The future of VOIP will be seen
• At the moment it appears as though it will be
  heavily used
• With heavy use though the QOS consideration gets
  more important
• Power issues will also need resolving
• Current PSTN networks have there own power supply
  in the event of an emergency!
• VOIP does not and relies on the mains power to a
  building or batteries