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VoIP { Voice Over IP }. What is VoIP? The transportation of packets containing voice data over a network (LAN, WAN or internet).

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Presentation on theme: "VoIP { Voice Over IP }. What is VoIP? The transportation of packets containing voice data over a network (LAN, WAN or internet)."— Presentation transcript:

1 VoIP { Voice Over IP }




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

6 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

7 Better Use of Resources { Beating a Dead Horse }

8 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

9 How Does it Work?

10 The Wireless Version VOWi-Fi

11 PSTN = Public Switched Telephone Networks IMS = IP Multimedia Subsystem

12 A Blip about SIP { I’m so clever } { I’m so clever }

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

14 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

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

16 1. INVITE From: 2. SIP/2.0 320 Moved temporarily Contact: Redirect Server Location Server Jeff.pulver pulver@von1 4. INVITE From: 3. ACK From: 5. SIP/2.0 200 OK To: 6. ACK From: Pulver@von1 SIP Redirect Mode

17 Can be stateful or stateless Hybrid Proxy Is Best Alternative Proxy ServerRedirect

18 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

19 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

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

21 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)


23 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!

24 Commercial Break {please stay tuned for your regularly scheduled broadcasting {please stay tuned for your regularly scheduled broadcasting

25 Some Problems Reliability Quality –Example: NATs prove to be big problem

26 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)


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

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

30 one smart decision among many many stupid ones Please stay tuned for the conclusion of your program, just after this

31 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

32 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

33 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

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

35 The End

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