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VoIP

VoIP. { Voice Over IP }. What is VoIP?. The transportation of packets containing voice data over a network (LAN, WAN or internet). Why is it Important?. Voice over IP does not just mean “voice.” Video, data conferencing Cost Convergence

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VoIP

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  1. VoIP { Voice Over IP }

  2. What is VoIP? The transportation of packets containing voice data over a network (LAN, WAN or internet).

  3. Why is it Important? • Voice over IP does not just mean “voice.” • Video, data conferencing • Cost • Convergence • Using high-speed internet connection for all voice, video, and data communications. • Reduce maintenance costs • Reduce deployments costs • Home has more options in service choices • Increased functionality

  4. Better Use of Resources { Beating a Dead Horse }

  5. How Does it Work? • Sound heard by computer at rate of 8,000 times per second or more • Uses CODEC (ulaw, alaw, gsm, ILBC, and others) • Speech CODECs are optimized to improve spoken words at the expense of sounds outside the frequency range of human speech • Placed into data packets – a single packet will contain 10 or more milliseconds (20 or 30 is more common) • PLC (Packet Loss Concealment) compensated for by CODEC • Redundancy • FEC (Forward Error Correction) • Delay • Jitter

  6. How Does it Work?

  7. The Wireless Version VOWi-Fi

  8. PSTN = Public Switched Telephone Networks IMS = IP Multimedia Subsystem

  9. A Blip about SIP{I’m so clever}

  10. SIP { Session Initiation Protocol } • Simple • SIP has only six methods • Transport-independent (application-layer): • Can be used with UDP, TCP, and more. • Readable • text based

  11. SIP { Session Initiation Protocol } Provides necessary protocol mechanisms so that end systems and proxy servers can provide services • call forwarding, including • equivalent to 700, 800, and 900 type calls • address-translation services • number delivery, where numbers can have naming scheme • personal mobility • the ability to reach a party under a single, location-independent address when the user changes terminals • negotiation • caller can be given choice how to reach the party • Internet telephony, mobile phone, answering service • caller and called authentication • invitations to multicast conferences

  12. pulver.com nortel.com jeff.pulver pulver@von1 user@nortel.com pulver@von1 Proxy server SIP Proxy Mode 1. INVITE sip:jeff.pulver@pulver.com SIP/2.0 From: sip:user@nortel.com 2. INVITE sip:pulver@von1 SIP/2.0 From: sip:user@nortel.com 3. SIP/2.0 200 ok From: sip:pulver@von1 Location Server 4. SIP/2.0 100 OK From: sip:jeff.pulver@pulver.com 5. ACK sip:jeff.pulver@pulver.com SIP/2.0 From: sip:user@nortel.com 6. ACK sip:pulver@von1 SIP/2.0 From: sip:user@nortel.com

  13. pulver.com nortel.com pulver@von1 Jeff.pulver user@nortel.com Pulver@von1 RedirectServer SIP Redirect Mode Location Server 1. INVITE sip:jeff.pulver@pulver.com From: sip:user@nortel.com 4. INVITE sip:pulver@von1.pulver.com From: user@nortel.com 5. SIP/2.0 200 OK To: user@nortel.com 2. SIP/2.0 320 Moved temporarily Contact: sip:pulver@von1.pulver.com 6. ACK sip:pulver@von1.pulver.com From: sip:user@nortel.com 3. ACK sip:jeff.pulver@pulverr.com From: sip:user@nortel.com

  14. Can be stateful or stateless Proxy Server Redirect Hybrid Proxy Is Best Alternative

  15. Stateful Proxy Servers • Maintains call context • Replicates User Agent Server/User Agent Client to process requests/responses • Call state and transaction state can be maintained • Forking proxies require state • TCP proxies must be stateful for reliability • Enhanced services require state for execution • Can populate billing information Services Dictate Statefulness of Proxy

  16. Stateless Proxy Servers • No call context • Response is not based on User Agent replication • Provides client anonymity • Restricted gateway access • High processing capacity • Allows for easier replication than stateful proxy • Can have semi-stateful proxy for ultimate benefits Stateless Proxies Geared for Capacity

  17. Can be stateful or stateless Proxy Server Redirect • High capacity • Flexible, network service implemenations • Minimal state overhead • Service execution pushed to client • Reliability achieved through replication • Scalability achieved through partitioning • Overload potential if not properly scaled • Hybrid (semi-stateful) model provides maximum benefits Hybrid Proxy Is Best Alternative

  18. H.323 • Complex • Easier to look at H.323 and SIP comparisons than to try to understand ‘how it works’ in a brief period of time • (big debate)

  19. What does that mean?! • Scalability: SIP • Reliability: H.323 • Speed: SIP • Standardized: H.323 • Most Flexibility with Services: SIP • Low Complexity: SIP • Features (as of right now): H.323 Everyone is biased!

  20. Commercial Break{please stay tuned for your regularly scheduled broadcasting

  21. Some Problems • Reliability • Quality • Example: NATs prove to be big problem

  22. STUN { Simple Traversal of UDP through NAT } • Used in residential NATs • allows for P2P connection through the NAT • Not 100% reliable • Does not work with Enterprise NATs (Symmetric)

  23. STUN

  24. TURN { Traversal Using Relay NAT } • Uses relay server to connect to single peer behind the NAT • 100% Reliable • Comes at great cost • Access bandwidth • Delay

  25. ICE { Interactive Connectivity Establishment } • Basically says to use STUN if at all possible, only using TURN as a last resort.

  26. one smart decision amongmany many stupid ones Please stay tuned for the conclusion of your program, just after this

  27. Problems with VoIP • Bandwidth Dependency • No internet = no phone • Poor connection = hate • Shared connection = unpredictable • Power Dependency • No power = no router/modem/ATA = no phone • No power = no 911 • Voice Quality • Delays, noise, echoes, strange sounds • Less robust than PSTN • Milliseconds mean everything

  28. Security Problems • Phreaking • Encryption is not common in SIP • Eavesdropping • Viruses and Malware • Soft-phones • DOS (Denial of Service) • SPIT (Spamming over Internet Telephony) • Easy to send to thousands of IP addresses (leads to phishing) • Call Tampering • Man-In-the-Middle Attacks • Particularly vulnerable

  29. Recent Legal News • Patents • Verizon won $58 million patent suit against Vonage • Web Telephony filed patent lawsuit with Verizon, Vonage, AT&T, EarthLink, and SunRocket • DoT clamp down in India • unlicensed foreign service providers

  30. In Conclusion, why use VoIP? Because even Jack Bauer Needs it

  31. The End

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