VoIP Conception and Implementation LANtel Telecommunication Corp. Senior Product Manager Jeremy Chan
Agenda <ul><li>What’s VoIP and IP Telephony (IPT) </li></ul><ul><li>VoIP Applications </li></ul><ul><li>VoIP QoS Issue </l...
<ul><li>What’s VoIP and IP Telephony (IPT) </li></ul>
<ul><li>VoIP :  </li></ul><ul><li>VoIP, Voice over Internet Protocol, is the technology that uses the Internet Protocol   ...
IPT (IP Telephony) <ul><li>IPT (IP Telephony) :  </li></ul><ul><li>An IP Communications System that provides a high availa...
Enterprise Voice Solution PSTN PBX PBX Router/GW Router/GW IP WAN Soft-Switch Soft-Switch Router/GW Router/GW IP WAN Appli...
Packet Voice Technology
<ul><li>VoIP Applications </li></ul>
Branch Office Application Branch 1 Branch N Server Farm PBX Telephone Telephone Telephone IWF IWF IWF HQ *IWF: Interworkin...
Interoffice Trunking Application   PBX Telephone PBX Telephone Packet Network
Interoffice Trunking Application
<ul><li>VoIP QoS Issue </li></ul>
VoIP QoS Issue <ul><li>Delay </li></ul><ul><ul><li>Algorithmic Delay </li></ul></ul><ul><ul><li>Processing Delay </li></ul...
Delay <ul><li>Algorithmic Delay </li></ul><ul><ul><li>Collect a frame of voice samples to be processed by the voice coder....
Delay <ul><li>Processing Delay </li></ul><ul><ul><li>Actual process of encoding and collecting the encoded samples into a ...
Delay <ul><li>Network Delay </li></ul><ul><ul><li>Physical medium and protocols used to transmit the voice data and by the...
Delay Causes Problems <ul><li>Echo </li></ul><ul><ul><li>Signal reflections of the speaker's voice from the far-end teleph...
Jitter <ul><li>Variable interpacket timing caused by the  </li></ul><ul><li>network a packet traverses. </li></ul><ul><li>...
Lost-Packet Compensation <ul><li>Lost packets can be an even more severe </li></ul><ul><li>problem, depending on the type ...
Echo Normal Telephony Call Normal Telephony Call with an Echo
Echo Compensation <ul><li>Signal reflections generated by the hybrid circuit that converts between a four-wire circuit (a ...
<ul><li>VoIP Architecture </li></ul>
VoIP–Embedded Software Architecture
<ul><li>Voice Packet Software Module </li></ul><ul><ul><li>digital-signal processor (DSP) </li></ul></ul><ul><li>Telephony...
<ul><li>VoIP Signaling </li></ul>
Signaling – H.323 <ul><li>H.323 </li></ul><ul><ul><li>Umbrella standard covering multimedia communications over LANs that ...
H.323 Protocol Stack Presentation Session Transport Data Link Physical Network Audio Signal Video Signal T.127 Data T.126 ...
H.323 protocols <ul><li>H.225   Covers narrow-band visual telephone services </li></ul><ul><li>H.225 Annex G </li></ul><ul...
H.323 Architecture
Typical H.323 Deployment
Signaling – MGCP, MAGACO <ul><li>Media Gateway Control Protocol </li></ul><ul><ul><li>Using packages model and providing a...
MGCP Architecture PBX T1/E1 FXO/FXS E&M Call Agent MGCP Voice Gateway MGCP RTP IP Phone ( MGCP Client ) IP Phone ( MGCP Cl...
Signaling – SIP <ul><li>Session Initiation Protocol </li></ul><ul><ul><li>Multimedia protocol that could take advantage of...
SIP Architecture
ENUM <ul><li>“ ENUM protocol is defined by RFC 2916, aiming at translating the numbers stemming form the ITU-T E.164 Recom...
ENUM  (Cont.) <ul><li>ENUM  is part of  Convergence </li></ul><ul><ul><li>ENUM is part of series of technical initiatives ...
VoIP Signaling Comparison
VoIP Signaling Comparison
 
<ul><li>Fax over IP </li></ul>
FAX over IP <ul><li>ITU and Internet Engineering Task Force (IETF) are working together to continue to evolve both the rea...
FoIP QoS <ul><li>Timing </li></ul><ul><ul><li>network delay </li></ul></ul><ul><ul><li>processing delay </li></ul></ul><ul...
Reference <ul><li>Cisco </li></ul><ul><ul><li>Introduce H.323 </li></ul></ul><ul><ul><li>SIP Presentation </li></ul></ul><...
<ul><li>Thank You </li></ul>
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VoIP Conception and Implementation

  1. 1. VoIP Conception and Implementation LANtel Telecommunication Corp. Senior Product Manager Jeremy Chan
  2. 2. Agenda <ul><li>What’s VoIP and IP Telephony (IPT) </li></ul><ul><li>VoIP Applications </li></ul><ul><li>VoIP QoS Issue </li></ul><ul><li>VoIP Architecture </li></ul><ul><li>VoIP Signaling </li></ul><ul><li>Fax over IP (FoIP) </li></ul>
  3. 3. <ul><li>What’s VoIP and IP Telephony (IPT) </li></ul>
  4. 4. <ul><li>VoIP : </li></ul><ul><li>VoIP, Voice over Internet Protocol, is the technology that uses the Internet Protocol to transmit voice conversation over a data network . </li></ul><ul><li>The primary advantages of moving voice over a data network are increased efficiency and decrease cost. </li></ul>VoIP
  5. 5. IPT (IP Telephony) <ul><li>IPT (IP Telephony) : </li></ul><ul><li>An IP Communications System that provides a high availability and scalability telephony system. </li></ul><ul><li>Provide support industry standards such as H.323, MGCP, SIP, JTAPI, TAPI, … etc. VoIP signal protocol. </li></ul>
  6. 6. Enterprise Voice Solution PSTN PBX PBX Router/GW Router/GW IP WAN Soft-Switch Soft-Switch Router/GW Router/GW IP WAN Application Servers PBX PBX
  7. 7. Packet Voice Technology
  8. 8. <ul><li>VoIP Applications </li></ul>
  9. 9. Branch Office Application Branch 1 Branch N Server Farm PBX Telephone Telephone Telephone IWF IWF IWF HQ *IWF: Interworking function Packet Network PSTN
  10. 10. Interoffice Trunking Application PBX Telephone PBX Telephone Packet Network
  11. 11. Interoffice Trunking Application
  12. 12. <ul><li>VoIP QoS Issue </li></ul>
  13. 13. VoIP QoS Issue <ul><li>Delay </li></ul><ul><ul><li>Algorithmic Delay </li></ul></ul><ul><ul><li>Processing Delay </li></ul></ul><ul><ul><li>Network Delay </li></ul></ul><ul><li>Jitter </li></ul><ul><li>Lost-Packet Compensation </li></ul><ul><li>Echo Compensation </li></ul>
  14. 14. Delay <ul><li>Algorithmic Delay </li></ul><ul><ul><li>Collect a frame of voice samples to be processed by the voice coder. </li></ul></ul><ul><ul><li>G.726 adaptive differential pulse-code modulation (ADPCM) (16, 24, 32, 40 kbps)—0.125 microseconds </li></ul></ul><ul><ul><li>G.728 LD–code excited linear prediction (CELP)(16 kbps)—2.5 milliseconds </li></ul></ul><ul><ul><li>G.729 CS–ACELP (8 kbps)—10 milliseconds </li></ul></ul><ul><ul><li>G.723.1 Multirate Coder (5.3, 6.3 kbps)—30 milliseconds </li></ul></ul>
  15. 15. Delay <ul><li>Processing Delay </li></ul><ul><ul><li>Actual process of encoding and collecting the encoded samples into a packet for transmission over the packet network. </li></ul></ul><ul><ul><li>The encoding delay is a function of both the processor execution time and the type of algorithm used. </li></ul></ul>
  16. 16. Delay <ul><li>Network Delay </li></ul><ul><ul><li>Physical medium and protocols used to transmit the voice data and by the buffers used to remove packet jitter on the receive side. </li></ul></ul><ul><ul><li>Network delay is a function of the capacity of the links in the network and the processing. </li></ul></ul>
  17. 17. Delay Causes Problems <ul><li>Echo </li></ul><ul><ul><li>Signal reflections of the speaker's voice from the far-end telephone equipment back into the speaker's ear. </li></ul></ul><ul><ul><li>Round-trip delay becomes greater than 50 milliseconds. (G.131) </li></ul></ul><ul><li>Talker overlap </li></ul><ul><ul><li>one talker stepping on the other talker's speech </li></ul></ul><ul><ul><li>the one-way delay becomes greater than 250 milliseconds. (G.114) </li></ul></ul>
  18. 18. Jitter <ul><li>Variable interpacket timing caused by the </li></ul><ul><li>network a packet traverses. </li></ul><ul><li>Removing jitter: collecting packets and holding them long enough to allow the slowest packets to arrive in time to be played in the correct sequence. </li></ul><ul><li>Causes additional delay </li></ul>
  19. 19. Lost-Packet Compensation <ul><li>Lost packets can be an even more severe </li></ul><ul><li>problem, depending on the type of packet </li></ul><ul><li>network that is being used. </li></ul><ul><li>Interpolate for lost speech packets by replaying the last packet received during the interval. </li></ul><ul><li>Send redundant information. </li></ul><ul><li>Use a hybrid approach with a much lower bandwidth voice coder to provide redundant information. </li></ul><ul><li>Avoiding and Managing network congestion </li></ul>
  20. 20. Echo Normal Telephony Call Normal Telephony Call with an Echo
  21. 21. Echo Compensation <ul><li>Signal reflections generated by the hybrid circuit that converts between a four-wire circuit (a separate transmit and receive pair) and a two-wire circuit (a single transmit and receive pair). </li></ul><ul><li>The round-trip delay through the network is almost always greater than 50 milliseconds. </li></ul><ul><li>ITU standard G.165 defines performance requirements that are currently required for echo cancellers. </li></ul>
  22. 22. <ul><li>VoIP Architecture </li></ul>
  23. 23. VoIP–Embedded Software Architecture
  24. 24. <ul><li>Voice Packet Software Module </li></ul><ul><ul><li>digital-signal processor (DSP) </li></ul></ul><ul><li>Telephony-Signaling Gateway Software Module </li></ul><ul><ul><li>Translating signaling into state changes used by the packet protocol module to set up connections. </li></ul></ul><ul><li>Packet Protocol Module </li></ul><ul><ul><li>processes signaling information and converts it. </li></ul></ul><ul><li>Network-Management Module </li></ul><ul><ul><li>Voice-management interface to configure and maintain the other modules </li></ul></ul>
  25. 25. <ul><li>VoIP Signaling </li></ul>
  26. 26. Signaling – H.323 <ul><li>H.323 </li></ul><ul><ul><li>Umbrella standard covering multimedia communications over LANs that do not provide a guaranteed Quality of Service. (H.323 v1) </li></ul></ul><ul><li>Entities </li></ul><ul><ul><li>Terminals </li></ul></ul><ul><ul><li>Gateways </li></ul></ul><ul><ul><li>Gatekeepers </li></ul></ul><ul><ul><li>MCUs </li></ul></ul><ul><li>Protocols </li></ul><ul><ul><li>Parts of H.225.0 - RAS, H.225 (Q.931) </li></ul></ul><ul><ul><li>H.245 </li></ul></ul><ul><ul><li>RTP/RTCP </li></ul></ul><ul><ul><li>Audio/video codecs </li></ul></ul>
  27. 27. H.323 Protocol Stack Presentation Session Transport Data Link Physical Network Audio Signal Video Signal T.127 Data T.126 RTCP H.235 UDP RAS RTP T.124 T.125/T.122 Supplementary Services Control H.245 H.225 TCP X.224.0 IP G.711 G.722 G.723.1 G.728 G.729 H.261 H.263 H.450.3 H.450.2 H.450.1
  28. 28. H.323 protocols <ul><li>H.225 Covers narrow-band visual telephone services </li></ul><ul><li>H.225 Annex G </li></ul><ul><li>H.235 Security and authentication </li></ul><ul><li>H.245 Negotiates channel usage and capabilities </li></ul><ul><li>H.450.1 Series defines Supplementary Services for H.323 </li></ul><ul><li>H.450.2 Call Transfer supplementary service for H.323 </li></ul><ul><li>H.450.3 Call diversion supplementary service for H.323 </li></ul><ul><li>H.450.4 Call Hold supplementary service </li></ul><ul><li>H.450.5 Call Park supplementary service </li></ul><ul><li>H.450.6 Call Waiting supplementary service </li></ul><ul><li>H.450.7 Message Waiting Indication supplementary service </li></ul><ul><li>H.450.8 Calling Party Name Presentation supplementary service </li></ul><ul><li>H.450.9 Completion of Calls to Busy Subscribers supplementary service </li></ul><ul><li>H.450.10 Call Offer supplementary service </li></ul><ul><li>H.450.11 Call Intrusion supplementary service </li></ul><ul><li>H.450.12 ANF-CMN supplementary service </li></ul><ul><li>H.261 Video stream for transport using the real-time transport </li></ul><ul><li>H.263 Bitstream in the RTP Q.931manages call setup and termination </li></ul><ul><li>RAS Manages registration, admission, status </li></ul><ul><li>RTCP RTP Control protocol </li></ul><ul><li>RTP Real-Time Transport </li></ul><ul><li>T.38 IP-based fax service maps </li></ul><ul><li>T.125 Multipoint Communication Service Protocol (MCS). </li></ul>
  29. 29. H.323 Architecture
  30. 30. Typical H.323 Deployment
  31. 31. Signaling – MGCP, MAGACO <ul><li>Media Gateway Control Protocol </li></ul><ul><ul><li>Using packages model and providing an centralized architecture where call control and services. </li></ul></ul><ul><ul><li>Controlling Telephony Gateways from external call control elements called media gateway controllers or call agents. </li></ul></ul><ul><li>Entities </li></ul><ul><ul><li>MGC (Media Gateway controller / Call agent) </li></ul></ul><ul><ul><li>MG (Media Gateway) </li></ul></ul><ul><li>Protocols </li></ul><ul><ul><li>MGCP v1 – RFC 2705 </li></ul></ul><ul><ul><li>H.248 (H.248 / MAGACO) – RFC 3525 </li></ul></ul><ul><ul><li>SDP (Session Definition Protocol) - RFC 3407 </li></ul></ul>
  32. 32. MGCP Architecture PBX T1/E1 FXO/FXS E&M Call Agent MGCP Voice Gateway MGCP RTP IP Phone ( MGCP Client ) IP Phone ( MGCP Client ) PSTN
  33. 33. Signaling – SIP <ul><li>Session Initiation Protocol </li></ul><ul><ul><li>Multimedia protocol that could take advantage of the Internet model for building VoIP networks and applications. Using distributed architecture. </li></ul></ul><ul><li>Entities </li></ul><ul><ul><li>User Agent </li></ul></ul><ul><ul><li>Gateways </li></ul></ul><ul><ul><li>Proxy Server </li></ul></ul><ul><ul><li>Redirect Server </li></ul></ul><ul><ul><li>Registrar Server </li></ul></ul><ul><li>Protocols (RFC 2543 v1, RFC 3261 v2) </li></ul><ul><ul><li>SDP ( Session Definition Protocol ) </li></ul></ul><ul><ul><li>URLs </li></ul></ul><ul><ul><li>DNSs </li></ul></ul><ul><ul><li>TRIP ( Telephony Routing Over IP </li></ul></ul>
  34. 34. SIP Architecture
  35. 35. ENUM <ul><li>“ ENUM protocol is defined by RFC 2916, aiming at translating the numbers stemming form the ITU-T E.164 Recommendation into Internet Domain Names; ENUM is an opportunity for developing the information society.” </li></ul><ul><li>“ As a matter of fact, ENUM allows to use a traditional telephone number in the context of different communications media, in particular those rising from the development of IP networks (e-mail, VoIP, …) and therefore, could facilitate the penetration of new applications into the mass market easily ( this market is accustomed to E.164 numbers).” </li></ul>
  36. 36. ENUM (Cont.) <ul><li>ENUM is part of Convergence </li></ul><ul><ul><li>ENUM is part of series of technical initiatives underway in both the IETF and ITU to develop Internet Telephony Standards. </li></ul></ul><ul><ul><ul><li>Call Setup – H.323 – SIP </li></ul></ul></ul><ul><ul><ul><li>Quality of Service – DIFFSERV – INTSERV – MPLS </li></ul></ul></ul><ul><ul><ul><li>PSTN – IP Interworking H.248/MEGACO </li></ul></ul></ul><ul><ul><ul><li>FAX – T.37, T.38 – RFC 2503 </li></ul></ul></ul><ul><ul><ul><li>Mobile – 3GPP related </li></ul></ul></ul><ul><li>ENUM is about new service creation </li></ul><ul><li>It must address naming and numbering issues </li></ul>
  37. 37. VoIP Signaling Comparison
  38. 38. VoIP Signaling Comparison
  39. 40. <ul><li>Fax over IP </li></ul>
  40. 41. FAX over IP <ul><li>ITU and Internet Engineering Task Force (IETF) are working together to continue to evolve both the real-time FoIP network standard (T.38) as well as the store-and-forward FoIP network standard (T.37). </li></ul><ul><li>T.38 is the fax transmission protocol selected for H.323. </li></ul>
  41. 42. FoIP QoS <ul><li>Timing </li></ul><ul><ul><li>network delay </li></ul></ul><ul><ul><li>processing delay </li></ul></ul><ul><ul><li>IWF must compensate for the loss of a fixed timing of messages over the packet network. </li></ul></ul><ul><li>Jitter </li></ul><ul><ul><li>collect packets and hold them long enough so that the slowest packets to arrive are still in time to be played in the correct sequence. </li></ul></ul><ul><li>Lost-Packet Compensation </li></ul><ul><ul><li>repeating information in subsequent frames </li></ul></ul><ul><ul><li>using an error-correcting protocol </li></ul></ul>
  42. 43. Reference <ul><li>Cisco </li></ul><ul><ul><li>Introduce H.323 </li></ul></ul><ul><ul><li>SIP Presentation </li></ul></ul><ul><li>REDCOM </li></ul><ul><ul><li>H.323 Tutorial </li></ul></ul><ul><li>IEC </li></ul><ul><ul><li>Voice and Fax over Internet Protocol (V/ FoIP ) </li></ul></ul><ul><li>ENUM.ORG </li></ul><ul><ul><li>Study Group A Presentation on ENUM </li></ul></ul><ul><li>IETF </li></ul><ul><ul><li>ftp://ftp.isi.edu/in-notes/rfc2916.txt -- ENUM Core Protocol </li></ul></ul><ul><ul><li>ftp://ftp.isi.edu/in-notes/rfc3261.txt -- SIP </li></ul></ul><ul><ul><li>ftp://ftp.isi.edu/in-notes/rfc2705.txt -- MGCP </li></ul></ul>
  43. 44. <ul><li>Thank You </li></ul>
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