SlideShare a Scribd company logo
1 of 25
Download to read offline
INTRODUCTION TO
                 VoIP
Elastix® Certification
© 2012, PALOSANTO SOLUTIONS All rights reserved. This documentation is confidential and
its intellectual property belongs to PaloSanto Solutions. Any unauthorized use, reproduction,
preparation of derivative works, performance, or display of this document, or software
represented by this document, without the express written permission of PaloSanto Solutions is
strictly prohibited. PaloSanto Solutions, Elastix and Elastix logo design, trademarks and/or
service marks belongs to Megatelcon S.A. all other trademarks, service marks, and trade
names are owned by their respective companies.
What is VoIP?

 Voice over IP or VoIP consists in transmitting voice over an IP
  protocol.

 This is a very broad concept and there are many protocol
  alternatives. It is truly a protocol soup.

 Voice is packetized so it can be transmitted over an IP
  network.

 The IP protocol was not designed specifically for transporting
  voice.
VoIP: a protocol soup
IP Protocol

 One of the most well-known protocols
 Its name comes from Internet Protocol.
 This protocol offers a service with ”no guarantees” and is also
  referred to as ”best effort”.
 The packets can arrive out of order, and be reordered at the
  destination.
 Some packets can even be lost on the way.
 This disorder and loss of packets can affect the quality of the
  voice.
 Despite all of this, intelligent ways have been found to solve
  these problems in the best way possible.
IP address (1)

 It's a unique number that identifies a host connected to an IP
  network.

 It's made up of 32 bits, or 4 octets. In practice a notation is
  used in which each octet is translated into decimal, and
  separated with a period. An example of an IP address is
  130.5.5.26.

 An IP address is composed in two parts: One identifies the
  host, and the other identifies the network to which that host
  belongs.

 To find these parts another parameter is used, called a
  network mask.
IP address (2)

 The network mask is a 32 bit binary number that is also
  represented in a notation that is similar to the IP address.

 It begins with ones and continues this way until it reaches a
  number of ones equal to the portion of the IP address that
  corresponds to the network.
IP address (3)

 Therefore, in the previous example we obtain an IP address
  of 130.5.5.26 with a mask of 255.255.255.0 belonging to the
  130.5.5.0 network.

 The previous mask was a 24 bit mask, since there were 24
  ”ones”.

 Once the network where the host is located is known it is
  easier to send the IP packets to their destination.

 Routers store tables of routes or rules on how to find other
  networks
IP Packets (1)
 An IP packet contains all the necessary information to arrive
  to its destination.

 It can be divided into two parts: the header and the payload.

 The header contains information that allows the packet to be
  delivered to its destination, and the payload retrieved.

 This header decreases slightly the quantity of information that
  can be transported since it occupies space.

 The payload can be used to encapsulate other protocols like
  UDP or TCP.
IP Packets (2)




 Header of an IP packet
IP routing
 Routers are necessary to direct packets on its way to a
  destination.

 Routers are devices with tables of routes.

 This “table of routes” is made up of destination networks, and
  for each one the IP address of the router to reach them.

 The router that provides a route to external networks is called
  a gateway.

 The IP packet that arrives at the router is examined to see
  what network it belongs to, the proper route is chosen, and
  the packet it is sent there.
TCP Protocol (1)

 Transport Control Protocol

 It is an IP protocol that allows packet retransmission, packet
  order management, and receipt acknowledgement.

 To achieve this goal, TCP carries additional information that
  adds weight to the packet. That is why it is not recommended
  for real time applications like voice.

 However, it can work for voice signaling.
TCP Protocol (2)

 TCP introduces the concept of port.

 A port is an abstraction that allows us to relate flows of data
  with services on the network.

 For example, port 80 corresponds to the Web service, or
  HTTP protocol.
UDP Protocol

 UDP (User Datagram Protocol) is another transport protocol.

 It divides information into packets called datagrams.

 This protocol doesn't care if the data arrives with errors or if it
  doesn´t arrive at all. That is the main difference with TCP.

 This is why it introduces little extra weight to the IP packet
  which makes it ideal for real-time applications like voice.
VoIP Signaling

 As in traditional telephony, it's necessary to signalize VoIP
  calls.

 There are some alternatives in signaling protocols, like SIP,
  H.323, MGCP, IAX2, and others.

 The most popular protocols on Asterisk are SIP and IAX2.

 Regarding SIP or H.323, many people confuse them and think
  that voice is transmitted through this protocol, but it is only
  used for signaling.
VoIP Transport

 RTP means Realtime Transport Protocol.

 The RTP protocol is the one that really transports encoded
  audio.

 RTP is transported over UDP.

 Using SIP, audio is transmitted over RTP after the network
  port between Elastix and the endpoint / telephone is
  negotiated.
Relationship between protocols
Voice codification

 Voice is adequately encoded for transmission.

 After encoding, it is transmitted over RTP.

 Encoding can serve to reduce the chance of error, as well as
  to minimize the amount of bandwidth used.

 To encode this data, an algorithm called a codec is used.

 There are several different codecs, each has pros and cons.
G.711
 One of the most widely used codecs of all time.

 Comes from the ITU-T standard that was released in 1972.

 Comes in two types called μ-Law (or u-law, primarily used in
  Europe) and a-Law (used in the USA).

 Advantage 1: Good voice quality since it uses 64kbit/s, that is a
  sampling of 8 bits at 8kHz.

 Advantage 2: It is already enabled in Elastix, it's not necessary to
  pay for it.

 Disadvantage: It uses a lot of bandwidth. It is not recommended
  for connections with low bandwidth.
G.729
 Also a very popular codec.

 Licensed by Intel.

 Advantage: It compresses voice very well without a significant
  loss of quality.

 Disadvantage 1: It is licensed          per   voice   channel,
  approximately USD$10 per channel.

 Disadvantage 2: Voice quality is lower than than G.711
GSM

 It is related to the cellular telephony standard GSM (Global
  System for Mobile communications), hence its name.

 It compresses voice very well, with a quality similar to cell
  phones.

 It is enabled by default in Elastix.

 Good as an alternative to G.729, although its audio quality is
  slightly inferior to G.729.
Protocol overload (1)
 The different protocols increase the total amount of data
  transmitted, in addition to the actual voice payload.

 Headers are added for Ethernet, IP, TCP/UDP, RTP.

 That makes the actual bandwidth for transmitting voice to be
  more than just what is required for the codec.

 For example, to transmit voice using G.711, in theory we should
  use 64Kbps (the payload of the codec), but we are really using
  95.2Kbps of BW.

 In codecs with more compression, overload is even more
  significant (percentage-wise).
Protocol overload (2)
Protocol overload (3)
– Let's calculate the bandwidth for G.711

•    Bytes transmitted every 20ms

– 38 + 20 + 12 + 8 + 160 = 238 bytes

•    Bits transmitted every 20ms

– 238 bytes * 8 bits/byte = 1904 bits

•    Bits transmitted every second

– 1904 bits/frame * 50 frames/seg. = 95,200 bits/second =
  95.2Kbps!
Comparing Codecs

   Table for the actual bandwidth for common codecs (using
    Ethernet):

             Codec       BW codec         BW actual (Ethernet)

         G.711            64 Kbps              95.2 Kbps
         G.726*           32 Kbps              63.2 Kbps
         iLBC*            15.2 Kbps            46.4 Kbps
         GSM              13 Kbps              43.7 Kbps
         G.729A            8 Kbps              39.2 Kbps


    * For these codecs, multiple data rates may be used.
More at:

www.elastixbook.com

More Related Content

What's hot (20)

Voip
VoipVoip
Voip
 
TCP/IP Modal
TCP/IP ModalTCP/IP Modal
TCP/IP Modal
 
multiplexing
multiplexingmultiplexing
multiplexing
 
Osi , tcp/ip protocol and Addressing
Osi , tcp/ip protocol and Addressing Osi , tcp/ip protocol and Addressing
Osi , tcp/ip protocol and Addressing
 
02 protocol architecture
02 protocol architecture02 protocol architecture
02 protocol architecture
 
OSI MODEL
OSI MODELOSI MODEL
OSI MODEL
 
Routing protocols
Routing protocolsRouting protocols
Routing protocols
 
WLAN:VPN Security
WLAN:VPN SecurityWLAN:VPN Security
WLAN:VPN Security
 
Voice-over-Internet Protocol (VoIP) ppt
Voice-over-Internet Protocol (VoIP) pptVoice-over-Internet Protocol (VoIP) ppt
Voice-over-Internet Protocol (VoIP) ppt
 
X.25 NETWORK PPROTOCOL
X.25 NETWORK PPROTOCOLX.25 NETWORK PPROTOCOL
X.25 NETWORK PPROTOCOL
 
IP PBX
IP PBXIP PBX
IP PBX
 
PSTN
PSTNPSTN
PSTN
 
IPv4 addressing and subnetting
IPv4 addressing and subnettingIPv4 addressing and subnetting
IPv4 addressing and subnetting
 
X.25 and frame relay
X.25 and frame relayX.25 and frame relay
X.25 and frame relay
 
Network protocols
Network protocolsNetwork protocols
Network protocols
 
Osi reference model
Osi reference modelOsi reference model
Osi reference model
 
Introduction to TCP/IP
Introduction to TCP/IPIntroduction to TCP/IP
Introduction to TCP/IP
 
transport protocols
transport protocolstransport protocols
transport protocols
 
Volte ppt
Volte pptVolte ppt
Volte ppt
 
Generations of network 1 g, 2g, 3g, 4g, 5g
Generations of network 1 g, 2g, 3g, 4g, 5gGenerations of network 1 g, 2g, 3g, 4g, 5g
Generations of network 1 g, 2g, 3g, 4g, 5g
 

Similar to Introduction to VoIP

Razin Kabir (063452556)
Razin Kabir (063452556)Razin Kabir (063452556)
Razin Kabir (063452556)mashiur
 
Shah Md Zobair(063560056)
Shah Md Zobair(063560056)Shah Md Zobair(063560056)
Shah Md Zobair(063560056)mashiur
 
ETE405-lec4.pptx
ETE405-lec4.pptxETE405-lec4.pptx
ETE405-lec4.pptxmashiur
 
Mohammad Faisal Kairm(073714556) Assignment 2
Mohammad Faisal Kairm(073714556) Assignment 2Mohammad Faisal Kairm(073714556) Assignment 2
Mohammad Faisal Kairm(073714556) Assignment 2mashiur
 
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...cscpconf
 
Practical Fundamentals of Voice over IP (VoIP) for Engineers and Technicians
Practical Fundamentals of Voice over IP (VoIP) for Engineers and TechniciansPractical Fundamentals of Voice over IP (VoIP) for Engineers and Technicians
Practical Fundamentals of Voice over IP (VoIP) for Engineers and TechniciansLiving Online
 
Intro tcpip-part1
Intro tcpip-part1Intro tcpip-part1
Intro tcpip-part1Kit Ramsey
 
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...csandit
 
VoIP and multimedia networking
VoIP and multimedia networkingVoIP and multimedia networking
VoIP and multimedia networkingsangusajjan
 
Voice over IP: Issues and Protocols
Voice over IP: Issues and ProtocolsVoice over IP: Issues and Protocols
Voice over IP: Issues and ProtocolsVideoguy
 
ETE405-lec7.pptx
ETE405-lec7.pptxETE405-lec7.pptx
ETE405-lec7.pptxmashiur
 
ETE405-lec7.pdf
ETE405-lec7.pdfETE405-lec7.pdf
ETE405-lec7.pdfmashiur
 
ETE405-lec7.ppt
ETE405-lec7.pptETE405-lec7.ppt
ETE405-lec7.pptmashiur
 

Similar to Introduction to VoIP (20)

Razin Kabir (063452556)
Razin Kabir (063452556)Razin Kabir (063452556)
Razin Kabir (063452556)
 
Shah Md Zobair(063560056)
Shah Md Zobair(063560056)Shah Md Zobair(063560056)
Shah Md Zobair(063560056)
 
Ch 2
Ch 2Ch 2
Ch 2
 
ETE405-lec4.pptx
ETE405-lec4.pptxETE405-lec4.pptx
ETE405-lec4.pptx
 
Mohammad Faisal Kairm(073714556) Assignment 2
Mohammad Faisal Kairm(073714556) Assignment 2Mohammad Faisal Kairm(073714556) Assignment 2
Mohammad Faisal Kairm(073714556) Assignment 2
 
Report
ReportReport
Report
 
Voip
VoipVoip
Voip
 
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
 
Practical Fundamentals of Voice over IP (VoIP) for Engineers and Technicians
Practical Fundamentals of Voice over IP (VoIP) for Engineers and TechniciansPractical Fundamentals of Voice over IP (VoIP) for Engineers and Technicians
Practical Fundamentals of Voice over IP (VoIP) for Engineers and Technicians
 
Intro tcpip-part1
Intro tcpip-part1Intro tcpip-part1
Intro tcpip-part1
 
Internet protocol
Internet protocolInternet protocol
Internet protocol
 
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
A NEW SYSTEM ON CHIP RECONFIGURABLE GATEWAY ARCHITECTURE FOR VOICE OVER INTER...
 
VoIP and multimedia networking
VoIP and multimedia networkingVoIP and multimedia networking
VoIP and multimedia networking
 
Skype
SkypeSkype
Skype
 
Voice over IP: Issues and Protocols
Voice over IP: Issues and ProtocolsVoice over IP: Issues and Protocols
Voice over IP: Issues and Protocols
 
ETE405-lec7.pptx
ETE405-lec7.pptxETE405-lec7.pptx
ETE405-lec7.pptx
 
A glance-at-voip
A glance-at-voipA glance-at-voip
A glance-at-voip
 
Ipv4 & ipv6
Ipv4 & ipv6Ipv4 & ipv6
Ipv4 & ipv6
 
ETE405-lec7.pdf
ETE405-lec7.pdfETE405-lec7.pdf
ETE405-lec7.pdf
 
ETE405-lec7.ppt
ETE405-lec7.pptETE405-lec7.ppt
ETE405-lec7.ppt
 

More from PaloSanto Solutions

Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...
Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...
Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...PaloSanto Solutions
 
Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?
Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?
Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?PaloSanto Solutions
 
Innovative technology for universal communication designed to involve the (he...
Innovative technology for universal communication designed to involve the (he...Innovative technology for universal communication designed to involve the (he...
Innovative technology for universal communication designed to involve the (he...PaloSanto Solutions
 
Queuemetrics esencial, de la implementación a reportes avanzadas
Queuemetrics esencial, de la implementación a reportes avanzadasQueuemetrics esencial, de la implementación a reportes avanzadas
Queuemetrics esencial, de la implementación a reportes avanzadasPaloSanto Solutions
 
La evolución de la telefonía IP a comunicaciones unificadas
La evolución de la telefonía IP a comunicaciones unificadasLa evolución de la telefonía IP a comunicaciones unificadas
La evolución de la telefonía IP a comunicaciones unificadasPaloSanto Solutions
 
Integrando encuestas automáticas con iSurveyX
Integrando encuestas automáticas con iSurveyXIntegrando encuestas automáticas con iSurveyX
Integrando encuestas automáticas con iSurveyXPaloSanto Solutions
 
Usando el módulo PIKE en Elastix MT
Usando el módulo PIKE en Elastix MTUsando el módulo PIKE en Elastix MT
Usando el módulo PIKE en Elastix MTPaloSanto Solutions
 
Todo lo lo que necesita saber para implementar FreePBX
Todo lo lo que necesita saber para implementar FreePBXTodo lo lo que necesita saber para implementar FreePBX
Todo lo lo que necesita saber para implementar FreePBXPaloSanto Solutions
 
Gestión de la Información de Desempeño con OpenNMS
Gestión de la Información de Desempeño con OpenNMSGestión de la Información de Desempeño con OpenNMS
Gestión de la Información de Desempeño con OpenNMSPaloSanto Solutions
 
Escalado y balanceo de carga de sistemas SIP
Escalado y balanceo de carga de sistemas SIPEscalado y balanceo de carga de sistemas SIP
Escalado y balanceo de carga de sistemas SIPPaloSanto Solutions
 
Elastix unified communications server cookbook
Elastix unified communications server cookbookElastix unified communications server cookbook
Elastix unified communications server cookbookPaloSanto Solutions
 
Seguridad en Asterisk: Un acercamiento detallado
Seguridad en Asterisk: Un acercamiento detalladoSeguridad en Asterisk: Un acercamiento detallado
Seguridad en Asterisk: Un acercamiento detalladoPaloSanto Solutions
 
Dynamic calls with Text To Speech
Dynamic calls with Text To SpeechDynamic calls with Text To Speech
Dynamic calls with Text To SpeechPaloSanto Solutions
 
Proceso de migración de telefonía tradicional a Elastix (Caso)
Proceso de migración de telefonía tradicional a Elastix (Caso)Proceso de migración de telefonía tradicional a Elastix (Caso)
Proceso de migración de telefonía tradicional a Elastix (Caso)PaloSanto Solutions
 
Building a new ecosystem for interoperable communications
Building a new ecosystem for interoperable communicationsBuilding a new ecosystem for interoperable communications
Building a new ecosystem for interoperable communicationsPaloSanto Solutions
 
Presentacion Hardware Elastix 2015 - Colombia
Presentacion Hardware Elastix 2015 - Colombia Presentacion Hardware Elastix 2015 - Colombia
Presentacion Hardware Elastix 2015 - Colombia PaloSanto Solutions
 
Módulo de Alta Disponibilidad de Elastix
Módulo de Alta Disponibilidad de ElastixMódulo de Alta Disponibilidad de Elastix
Módulo de Alta Disponibilidad de ElastixPaloSanto Solutions
 

More from PaloSanto Solutions (20)

Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...
Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...
Tres componentes fundamentales de un buen PBX IP: seguridad, alta disponibili...
 
Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?
Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?
Voip y Big Data, ¿Cómo aplicar analytics a la VoIP?
 
Innovative technology for universal communication designed to involve the (he...
Innovative technology for universal communication designed to involve the (he...Innovative technology for universal communication designed to involve the (he...
Innovative technology for universal communication designed to involve the (he...
 
Queuemetrics esencial, de la implementación a reportes avanzadas
Queuemetrics esencial, de la implementación a reportes avanzadasQueuemetrics esencial, de la implementación a reportes avanzadas
Queuemetrics esencial, de la implementación a reportes avanzadas
 
La evolución de la telefonía IP a comunicaciones unificadas
La evolución de la telefonía IP a comunicaciones unificadasLa evolución de la telefonía IP a comunicaciones unificadas
La evolución de la telefonía IP a comunicaciones unificadas
 
WebRTC … ¡vamos a discar!
WebRTC … ¡vamos a discar!WebRTC … ¡vamos a discar!
WebRTC … ¡vamos a discar!
 
Integrando encuestas automáticas con iSurveyX
Integrando encuestas automáticas con iSurveyXIntegrando encuestas automáticas con iSurveyX
Integrando encuestas automáticas con iSurveyX
 
Usando el módulo PIKE en Elastix MT
Usando el módulo PIKE en Elastix MTUsando el módulo PIKE en Elastix MT
Usando el módulo PIKE en Elastix MT
 
Todo lo lo que necesita saber para implementar FreePBX
Todo lo lo que necesita saber para implementar FreePBXTodo lo lo que necesita saber para implementar FreePBX
Todo lo lo que necesita saber para implementar FreePBX
 
Gestión de la Información de Desempeño con OpenNMS
Gestión de la Información de Desempeño con OpenNMSGestión de la Información de Desempeño con OpenNMS
Gestión de la Información de Desempeño con OpenNMS
 
Escalado y balanceo de carga de sistemas SIP
Escalado y balanceo de carga de sistemas SIPEscalado y balanceo de carga de sistemas SIP
Escalado y balanceo de carga de sistemas SIP
 
Elastix unified communications server cookbook
Elastix unified communications server cookbookElastix unified communications server cookbook
Elastix unified communications server cookbook
 
Seguridad en Asterisk: Un acercamiento detallado
Seguridad en Asterisk: Un acercamiento detalladoSeguridad en Asterisk: Un acercamiento detallado
Seguridad en Asterisk: Un acercamiento detallado
 
Dynamic calls with Text To Speech
Dynamic calls with Text To SpeechDynamic calls with Text To Speech
Dynamic calls with Text To Speech
 
Proceso de migración de telefonía tradicional a Elastix (Caso)
Proceso de migración de telefonía tradicional a Elastix (Caso)Proceso de migración de telefonía tradicional a Elastix (Caso)
Proceso de migración de telefonía tradicional a Elastix (Caso)
 
Building a new ecosystem for interoperable communications
Building a new ecosystem for interoperable communicationsBuilding a new ecosystem for interoperable communications
Building a new ecosystem for interoperable communications
 
Asterisk: the future is at REST
Asterisk: the future is at RESTAsterisk: the future is at REST
Asterisk: the future is at REST
 
Presentacion Hardware Elastix 2015 - Colombia
Presentacion Hardware Elastix 2015 - Colombia Presentacion Hardware Elastix 2015 - Colombia
Presentacion Hardware Elastix 2015 - Colombia
 
Voicemail Avanzado
Voicemail AvanzadoVoicemail Avanzado
Voicemail Avanzado
 
Módulo de Alta Disponibilidad de Elastix
Módulo de Alta Disponibilidad de ElastixMódulo de Alta Disponibilidad de Elastix
Módulo de Alta Disponibilidad de Elastix
 

Recently uploaded

How Accurate are Carbon Emissions Projections?
How Accurate are Carbon Emissions Projections?How Accurate are Carbon Emissions Projections?
How Accurate are Carbon Emissions Projections?IES VE
 
Bird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystemBird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystemAsko Soukka
 
OpenShift Commons Paris - Choose Your Own Observability Adventure
OpenShift Commons Paris - Choose Your Own Observability AdventureOpenShift Commons Paris - Choose Your Own Observability Adventure
OpenShift Commons Paris - Choose Your Own Observability AdventureEric D. Schabell
 
COMPUTER 10 Lesson 8 - Building a Website
COMPUTER 10 Lesson 8 - Building a WebsiteCOMPUTER 10 Lesson 8 - Building a Website
COMPUTER 10 Lesson 8 - Building a Websitedgelyza
 
Cybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptxCybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptxGDSC PJATK
 
9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding Team9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding TeamAdam Moalla
 
Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024D Cloud Solutions
 
20230202 - Introduction to tis-py
20230202 - Introduction to tis-py20230202 - Introduction to tis-py
20230202 - Introduction to tis-pyJamie (Taka) Wang
 
UiPath Community: AI for UiPath Automation Developers
UiPath Community: AI for UiPath Automation DevelopersUiPath Community: AI for UiPath Automation Developers
UiPath Community: AI for UiPath Automation DevelopersUiPathCommunity
 
AI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just MinutesAI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just MinutesMd Hossain Ali
 
activity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdf
activity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdf
activity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdfJamie (Taka) Wang
 
Building Your Own AI Instance (TBLC AI )
Building Your Own AI Instance (TBLC AI )Building Your Own AI Instance (TBLC AI )
Building Your Own AI Instance (TBLC AI )Brian Pichman
 
UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7DianaGray10
 
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...Aggregage
 
Videogame localization & technology_ how to enhance the power of translation.pdf
Videogame localization & technology_ how to enhance the power of translation.pdfVideogame localization & technology_ how to enhance the power of translation.pdf
Videogame localization & technology_ how to enhance the power of translation.pdfinfogdgmi
 
UiPath Studio Web workshop series - Day 8
UiPath Studio Web workshop series - Day 8UiPath Studio Web workshop series - Day 8
UiPath Studio Web workshop series - Day 8DianaGray10
 
Igniting Next Level Productivity with AI-Infused Data Integration Workflows
Igniting Next Level Productivity with AI-Infused Data Integration WorkflowsIgniting Next Level Productivity with AI-Infused Data Integration Workflows
Igniting Next Level Productivity with AI-Infused Data Integration WorkflowsSafe Software
 

Recently uploaded (20)

How Accurate are Carbon Emissions Projections?
How Accurate are Carbon Emissions Projections?How Accurate are Carbon Emissions Projections?
How Accurate are Carbon Emissions Projections?
 
Bird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystemBird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystem
 
20230104 - machine vision
20230104 - machine vision20230104 - machine vision
20230104 - machine vision
 
OpenShift Commons Paris - Choose Your Own Observability Adventure
OpenShift Commons Paris - Choose Your Own Observability AdventureOpenShift Commons Paris - Choose Your Own Observability Adventure
OpenShift Commons Paris - Choose Your Own Observability Adventure
 
COMPUTER 10 Lesson 8 - Building a Website
COMPUTER 10 Lesson 8 - Building a WebsiteCOMPUTER 10 Lesson 8 - Building a Website
COMPUTER 10 Lesson 8 - Building a Website
 
Cybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptxCybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptx
 
9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding Team9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding Team
 
20150722 - AGV
20150722 - AGV20150722 - AGV
20150722 - AGV
 
Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024
 
201610817 - edge part1
201610817 - edge part1201610817 - edge part1
201610817 - edge part1
 
20230202 - Introduction to tis-py
20230202 - Introduction to tis-py20230202 - Introduction to tis-py
20230202 - Introduction to tis-py
 
UiPath Community: AI for UiPath Automation Developers
UiPath Community: AI for UiPath Automation DevelopersUiPath Community: AI for UiPath Automation Developers
UiPath Community: AI for UiPath Automation Developers
 
AI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just MinutesAI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just Minutes
 
activity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdf
activity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdf
activity_diagram_combine_v4_20190827.pdfactivity_diagram_combine_v4_20190827.pdf
 
Building Your Own AI Instance (TBLC AI )
Building Your Own AI Instance (TBLC AI )Building Your Own AI Instance (TBLC AI )
Building Your Own AI Instance (TBLC AI )
 
UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7
 
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
 
Videogame localization & technology_ how to enhance the power of translation.pdf
Videogame localization & technology_ how to enhance the power of translation.pdfVideogame localization & technology_ how to enhance the power of translation.pdf
Videogame localization & technology_ how to enhance the power of translation.pdf
 
UiPath Studio Web workshop series - Day 8
UiPath Studio Web workshop series - Day 8UiPath Studio Web workshop series - Day 8
UiPath Studio Web workshop series - Day 8
 
Igniting Next Level Productivity with AI-Infused Data Integration Workflows
Igniting Next Level Productivity with AI-Infused Data Integration WorkflowsIgniting Next Level Productivity with AI-Infused Data Integration Workflows
Igniting Next Level Productivity with AI-Infused Data Integration Workflows
 

Introduction to VoIP

  • 1. INTRODUCTION TO VoIP Elastix® Certification © 2012, PALOSANTO SOLUTIONS All rights reserved. This documentation is confidential and its intellectual property belongs to PaloSanto Solutions. Any unauthorized use, reproduction, preparation of derivative works, performance, or display of this document, or software represented by this document, without the express written permission of PaloSanto Solutions is strictly prohibited. PaloSanto Solutions, Elastix and Elastix logo design, trademarks and/or service marks belongs to Megatelcon S.A. all other trademarks, service marks, and trade names are owned by their respective companies.
  • 2. What is VoIP?  Voice over IP or VoIP consists in transmitting voice over an IP protocol.  This is a very broad concept and there are many protocol alternatives. It is truly a protocol soup.  Voice is packetized so it can be transmitted over an IP network.  The IP protocol was not designed specifically for transporting voice.
  • 4. IP Protocol  One of the most well-known protocols  Its name comes from Internet Protocol.  This protocol offers a service with ”no guarantees” and is also referred to as ”best effort”.  The packets can arrive out of order, and be reordered at the destination.  Some packets can even be lost on the way.  This disorder and loss of packets can affect the quality of the voice.  Despite all of this, intelligent ways have been found to solve these problems in the best way possible.
  • 5. IP address (1)  It's a unique number that identifies a host connected to an IP network.  It's made up of 32 bits, or 4 octets. In practice a notation is used in which each octet is translated into decimal, and separated with a period. An example of an IP address is 130.5.5.26.  An IP address is composed in two parts: One identifies the host, and the other identifies the network to which that host belongs.  To find these parts another parameter is used, called a network mask.
  • 6. IP address (2)  The network mask is a 32 bit binary number that is also represented in a notation that is similar to the IP address.  It begins with ones and continues this way until it reaches a number of ones equal to the portion of the IP address that corresponds to the network.
  • 7. IP address (3)  Therefore, in the previous example we obtain an IP address of 130.5.5.26 with a mask of 255.255.255.0 belonging to the 130.5.5.0 network.  The previous mask was a 24 bit mask, since there were 24 ”ones”.  Once the network where the host is located is known it is easier to send the IP packets to their destination.  Routers store tables of routes or rules on how to find other networks
  • 8. IP Packets (1)  An IP packet contains all the necessary information to arrive to its destination.  It can be divided into two parts: the header and the payload.  The header contains information that allows the packet to be delivered to its destination, and the payload retrieved.  This header decreases slightly the quantity of information that can be transported since it occupies space.  The payload can be used to encapsulate other protocols like UDP or TCP.
  • 9. IP Packets (2) Header of an IP packet
  • 10. IP routing  Routers are necessary to direct packets on its way to a destination.  Routers are devices with tables of routes.  This “table of routes” is made up of destination networks, and for each one the IP address of the router to reach them.  The router that provides a route to external networks is called a gateway.  The IP packet that arrives at the router is examined to see what network it belongs to, the proper route is chosen, and the packet it is sent there.
  • 11. TCP Protocol (1)  Transport Control Protocol  It is an IP protocol that allows packet retransmission, packet order management, and receipt acknowledgement.  To achieve this goal, TCP carries additional information that adds weight to the packet. That is why it is not recommended for real time applications like voice.  However, it can work for voice signaling.
  • 12. TCP Protocol (2)  TCP introduces the concept of port.  A port is an abstraction that allows us to relate flows of data with services on the network.  For example, port 80 corresponds to the Web service, or HTTP protocol.
  • 13. UDP Protocol  UDP (User Datagram Protocol) is another transport protocol.  It divides information into packets called datagrams.  This protocol doesn't care if the data arrives with errors or if it doesn´t arrive at all. That is the main difference with TCP.  This is why it introduces little extra weight to the IP packet which makes it ideal for real-time applications like voice.
  • 14. VoIP Signaling  As in traditional telephony, it's necessary to signalize VoIP calls.  There are some alternatives in signaling protocols, like SIP, H.323, MGCP, IAX2, and others.  The most popular protocols on Asterisk are SIP and IAX2.  Regarding SIP or H.323, many people confuse them and think that voice is transmitted through this protocol, but it is only used for signaling.
  • 15. VoIP Transport  RTP means Realtime Transport Protocol.  The RTP protocol is the one that really transports encoded audio.  RTP is transported over UDP.  Using SIP, audio is transmitted over RTP after the network port between Elastix and the endpoint / telephone is negotiated.
  • 17. Voice codification  Voice is adequately encoded for transmission.  After encoding, it is transmitted over RTP.  Encoding can serve to reduce the chance of error, as well as to minimize the amount of bandwidth used.  To encode this data, an algorithm called a codec is used.  There are several different codecs, each has pros and cons.
  • 18. G.711  One of the most widely used codecs of all time.  Comes from the ITU-T standard that was released in 1972.  Comes in two types called μ-Law (or u-law, primarily used in Europe) and a-Law (used in the USA).  Advantage 1: Good voice quality since it uses 64kbit/s, that is a sampling of 8 bits at 8kHz.  Advantage 2: It is already enabled in Elastix, it's not necessary to pay for it.  Disadvantage: It uses a lot of bandwidth. It is not recommended for connections with low bandwidth.
  • 19. G.729  Also a very popular codec.  Licensed by Intel.  Advantage: It compresses voice very well without a significant loss of quality.  Disadvantage 1: It is licensed per voice channel, approximately USD$10 per channel.  Disadvantage 2: Voice quality is lower than than G.711
  • 20. GSM  It is related to the cellular telephony standard GSM (Global System for Mobile communications), hence its name.  It compresses voice very well, with a quality similar to cell phones.  It is enabled by default in Elastix.  Good as an alternative to G.729, although its audio quality is slightly inferior to G.729.
  • 21. Protocol overload (1)  The different protocols increase the total amount of data transmitted, in addition to the actual voice payload.  Headers are added for Ethernet, IP, TCP/UDP, RTP.  That makes the actual bandwidth for transmitting voice to be more than just what is required for the codec.  For example, to transmit voice using G.711, in theory we should use 64Kbps (the payload of the codec), but we are really using 95.2Kbps of BW.  In codecs with more compression, overload is even more significant (percentage-wise).
  • 23. Protocol overload (3) – Let's calculate the bandwidth for G.711 • Bytes transmitted every 20ms – 38 + 20 + 12 + 8 + 160 = 238 bytes • Bits transmitted every 20ms – 238 bytes * 8 bits/byte = 1904 bits • Bits transmitted every second – 1904 bits/frame * 50 frames/seg. = 95,200 bits/second = 95.2Kbps!
  • 24. Comparing Codecs  Table for the actual bandwidth for common codecs (using Ethernet): Codec BW codec BW actual (Ethernet) G.711 64 Kbps 95.2 Kbps G.726* 32 Kbps 63.2 Kbps iLBC* 15.2 Kbps 46.4 Kbps GSM 13 Kbps 43.7 Kbps G.729A 8 Kbps 39.2 Kbps * For these codecs, multiple data rates may be used.