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Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
Presentation - HEAnet, Ireland's National Education ...
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Presentation - HEAnet, Ireland's National Education ...

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  • 1. VoIP in Context <ul><li>Niall O’Reilly, University College Dublin IT Services </li></ul><ul><li>HEAnet National Networking Conference 2006 </li></ul>
  • 2. VoIP in Context <ul><li>Strategic issues </li></ul><ul><li>How VoIP works </li></ul><ul><li>Market issues </li></ul><ul><li>Interoperation with POTS </li></ul><ul><li>Interoperation among VoIP services </li></ul><ul><li>Strategic options </li></ul>
  • 3. VoIP in Context <ul><li>What context would that be ... ? </li></ul>
  • 4. VoIP in Context <ul><li>Strategic issues </li></ul><ul><li>How VoIP works </li></ul><ul><li>Interoperation </li></ul><ul><li>Strategic options </li></ul>
  • 5. VoIP: Strategic Issues <ul><li>Global or local scope? </li></ul><ul><li>Build, buy, or leave it to the users? </li></ul><ul><li>Proprietary or standards-based? </li></ul><ul><li>Branding? </li></ul><ul><li>First, see how it works ... </li></ul>
  • 6. How VoIP works <ul><li>Different flavours: Standards: SIP, H.323, Services: Skype, IP-TSPs </li></ul><ul><li>Similar requirements: Find called party Set up call </li></ul><ul><li>Look at SIP ... </li></ul>
  • 7. SIP — direct call INVITE sip: 10.17.243.34 100 Trying - ACK RTP session (voice, video, etc) Artificially simple case: caller knows where my phone is Caller’s phone My phone 200 OK 180 Ringing - 192.168.19.76 10.17.243.34
  • 8. SIP — where did he go? 10.17.243.34 Usual case: my phone is nomadic Caller’s phone My phone 10.97.1.5
  • 9. SIP servers keep track 10.17.243.34 SIP Registrar: tracks last REGISTER event Caller’s phone My phone 10.97.1.5 SIP Registrar server sip.example.net Caller’s SIP server (if any)
  • 10. SIP — using servers INVITE sip: [email_address] ACK RTP session (voice, video, etc) Servers broker call using SIP Payload is carried peer-to-peer INVITE INVITE 200 OK Control Transport Data
  • 11. VoIP compared to e-mail Submit Difference: mail servers carry payload Forward Retrieve Message queue Message store Control & Data Transport
  • 12. VoIP compared to POTS Place call Difference: Payload travels over provider’s resources Set up circuit Terminate call Voice traffic over circuit Vertically integrated: no separation of Control, Data, and Transport
  • 13. Interoperation <ul><li>Technology: gateways, mapping </li></ul><ul><li>Service management </li></ul><ul><li>Business model </li></ul><ul><li>POTS is centre-stage </li></ul>
  • 14. Interoperation <ul><li>Within POTS </li></ul><ul><li>VoIP/POTS </li></ul><ul><li>Within VoIP </li></ul>
  • 15. POTS Interoperation <ul><li>Dial plan what can be dialled (DTMF-12) </li></ul><ul><li>Numbering plan what can be reached (E.164) </li></ul><ul><li>Interconnection specific number ranges — routing codes </li></ul><ul><li>Cascaded charges terminating operator in control </li></ul><ul><li>Fewer hops best for business </li></ul>Originating Operator Terminating Operator Transit Operator
  • 16. <ul><li>POTS dominates (Metcalfe’s Law) </li></ul><ul><li>Address (URL, number) mapping </li></ul><ul><li>Media conversion </li></ul><ul><li>Business relationship </li></ul>VoIP/POTS Interoperation
  • 17. <ul><li>POTS uses [*#0-9] — VoIP side must accommodate </li></ul><ul><li>Customer aliases facilitate this — Real POTS phone number (E.164) — Two-stage dialling to “extension” — extension@example.org — username@example.org </li></ul>VoIP/POTS Address Mapping
  • 18. <ul><li>Numbering plan POTS: numeric only VoIP: URL space or per-operator number blocks </li></ul><ul><li>Interconnection must map (relevant parts of) numbering plans POTS to VoIP: ENUM can find matching URL for number VoIP to POTS: configuration; ENUM enables POTS bypass </li></ul><ul><li>Successive gateways degrade quality due to lossy trans-coding </li></ul>VoIP/POTS Interoperation
  • 19. <ul><li>Different business model </li></ul><ul><li>Cascaded charges on POTS side from POTS: gateway immediately (keep entire fee! from VOIP: exit to POTS late (keep bigger share of fee!) </li></ul><ul><li>Paradox: VoIP is good for operator! </li></ul>VoIP/POTS Interoperation
  • 20. <ul><li>Dial plan DTMF (0-9, #, *) URL (user@domain) </li></ul><ul><li>Numbering plan URL space </li></ul><ul><li>Interconnection Configuration tables — maintenance! DNS is so much simpler ENUM: maps number to URL SPIT: Spam over IP Telephony </li></ul><ul><li>Reachability decoupled from cost </li></ul>VoIP Interoperation Originating IP-TSP Terminating IP-TSP Internet: ISPs & Transit
  • 21. VoIP Interoperation <ul><li>Can be just like e-mail: sip:user@domain </li></ul><ul><li>URL drives DNS to locate destination </li></ul><ul><li>DNS RR-types: SRV, A </li></ul><ul><li>Provider issues: — “walled garden” vs “public park” </li></ul><ul><li>Customer issues: NAT, firewalls </li></ul>
  • 22. VoIP Interoperation <ul><li>Technology open — just like e-mail </li></ul><ul><li>Operator business model varies — “walled garden” vs “public park” </li></ul><ul><li>Obstacles may be significant — NAT, firewall </li></ul>
  • 23. VoIP Interoperation <ul><li>Static routes support bilateral agreements </li></ul><ul><li>VoIP “islands” may need to route via POTS — involving duration charges, double transcoding </li></ul><ul><li>ENUM maps numbers to URLs — but not yet widely (enough) deployed </li></ul><ul><li>Not unlike e-mail before MX records </li></ul>
  • 24. <ul><li>Example </li></ul><ul><ul><li>[Remember “!” and “%” for e-mail] </li></ul></ul><ul><ul><li>*8 *4yy 8972xxxx </li></ul></ul><ul><ul><li>sip: 8972xxxx @example.org </li></ul></ul><ul><ul><li>sip:someuser@example.org </li></ul></ul>Address Mapping
  • 25. <ul><li>Encodes E.164 numbers as domain names — no “short codes” or “operator-specific” </li></ul><ul><li>Standard algorithm to determine URL — DDDS: RFC 3401ff </li></ul><ul><li>Not yet generally deployed </li></ul>ENUM
  • 26. Strategic options <ul><li>Global or local scope? </li></ul><ul><li>Build, buy, or leave it to the users? </li></ul><ul><li>Proprietary or standards-based? </li></ul><ul><li>Branding? </li></ul>
  • 27. Local or global scope <ul><li>Technology substitution </li></ul><ul><li>“Free” long-distance phone-calls </li></ul><ul><li>Extend footprint of internal PBX — teleworkers, conference-goers </li></ul>
  • 28. Build, buy, or step aside <ul><li>In-house like e-mail linked to other administrative processes </li></ul><ul><li>Outsource to existing IP-TSP established expertise </li></ul><ul><li>Skype — just works walled garden with gates (charged Skype-in, -out) </li></ul><ul><li>Gizmo — has free SIP-out </li></ul>
  • 29. Standard or proprietary <ul><li>Cisco, Nortel, ... </li></ul><ul><li>Skype </li></ul><ul><li>Standard Interoperability Exploits DNS for provisioning Open Source: SER, Asterisk </li></ul>
  • 30. Branding <ul><li>What goes on the stationery? </li></ul><ul><li>Skype: joe_user </li></ul><ul><li>IP-TSP: sip:Niall.oReilly.UCD@example.ie </li></ul><ul><li>Own-brand: sip:First.Last@ucd.ie </li></ul><ul><li>E.164: +353-1-716-xxxx </li></ul>
  • 31. Strategic options <ul><li>Global or local scope? </li></ul><ul><li>Build, buy, or leave it to the users? </li></ul><ul><li>Proprietary or standards-based? </li></ul><ul><li>Branding? </li></ul><ul><li>Know what you require, then decide </li></ul>
  • 32. VoIP Resources <ul><li>Terena VoIP Cookbook (2004) </li></ul><ul><li>Richard Stastny’s Blog http://voipandenum.blogspot.com </li></ul><ul><li>iptel.org </li></ul>
  • 33. ?

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