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Questions and Answers

What is the primary function of SIP in user location?

  • User availability
  • Name translation (correct)
  • Session setup
  • User capabilities

    • Which of the following is NOT a primary function of SIP?

  • Network topology (correct)
  • Session setup
  • User location and name translation
  • User capabilities

    • What is the purpose of session management in SIP?

  • To establish communication sessions
  • To modify session parameters and invoke services (correct)
  • To provide user availability information
  • To translate user names

    • What is VoIP in the context of SIP?

    <p>Voice over IP telephony</p> Signup and view all the answers

    How does SIP handle mobile capability?

    <p>Using name mapping and redirection servers</p> Signup and view all the answers

    What is the purpose of SIP requests and responses?

    <p>To exchange information between SIP entities</p> Signup and view all the answers

    What is the primary purpose of user capabilities in SIP?

    <p>To agree on different features supported</p> Signup and view all the answers

    What is the role of SIP in IP telephony?

    <p>To establish, modify, and terminate sessions</p> Signup and view all the answers

    What message is sent from the PBX to the client after a successful registration?

    <p>OK 200</p> Signup and view all the answers

    What type of message is sent from a client to the PBX to establish a communication line?

    <p>INVITE</p> Signup and view all the answers

    What response is sent from the called client to the PBX after receiving an INVITE message?

    <p>TRYING</p> Signup and view all the answers

    What message is sent from the client to the PBX to end a call?

    <p>BYE</p> Signup and view all the answers

    What happens after the called client accepts the call?

    <p>The communication line is established and the PBX gets out the communication</p> Signup and view all the answers

    What is the purpose of the ACK message in ending a call?

    <p>To notify the client that the remote party acknowledged the end call request</p> Signup and view all the answers

    How does the communication flow after the connection is established?

    <p>The communication is made directly between the two VoIP clients</p> Signup and view all the answers

    What happens to the software tools and hardware devices after the communication line is closed?

    <p>They are stopped</p> Signup and view all the answers

    What is the primary function of a Media Gateway in a VoIP network?

    <p>To connect different physical networks for end-to-end connectivity</p> Signup and view all the answers

    What is the main difference between a hard phone and a softphone?

    <p>Hard phones are traditional telephone devices, softphones are software solutions</p> Signup and view all the answers

    What is the primary function of an Analog Terminal Adapter (ATA)?

    <p>To perform analog and digital conversions between a traditional analog phone and the broadband modem</p> Signup and view all the answers

    What is the call agent responsible for?

    <p>Call routing, network signaling, and billing</p> Signup and view all the answers

    What is the purpose of a soft switch in a VoIP network?

    <p>To function as a switchboard for VoIP communication</p> Signup and view all the answers

    What is the main hardware component used by a softphone?

    <p>All of the above</p> Signup and view all the answers

    What is the main function of a Media Gateway in terms of VoIP circuits?

    <p>To connect a VoIP circuit to a PSTN circuit</p> Signup and view all the answers

    What is the purpose of an ATA's two ports?

    <p>To enable users to use VoIP service with an existing phone</p> Signup and view all the answers

    What is the primary function of VoIP technology?

    <p>To encode voice information into a digital format</p> Signup and view all the answers

    What is the role of the soft switch in VoIP technology?

    <p>To control connection between end-points where no end-to-end VoIP connection is available</p> Signup and view all the answers

    What is the process of encoding voice information into digital format in VoIP?

    <p>Voice digitization</p> Signup and view all the answers

    What is the role of the media gateway in VoIP technology?

    <p>Part of the soft switch</p> Signup and view all the answers

    What is the final step in the process of VoIP communication?

    <p>Voice decoding at the remote end</p> Signup and view all the answers

    What is the primary difference between VoIP and traditional telephone communication?

    <p>The type of network used</p> Signup and view all the answers

    What is the role of the call agent in VoIP technology?

    <p>Part of the soft switch</p> Signup and view all the answers

    What is the primary advantage of VoIP technology?

    <p>It allows for communication through the Internet Protocol</p> Signup and view all the answers

    What is the purpose of the REGISTER request in SIP communication?

    <p>To authenticate a VoIP client with the PBX</p> Signup and view all the answers

    What happens after the connection is established between two VoIP clients?

    <p>The two clients start communicating directly</p> Signup and view all the answers

    What type of messages are sent between a VoIP client and the PBX during registration?

    <p>SIP requests and SIP responses</p> Signup and view all the answers

    What is the role of the PBX in a VoIP communication flow?

    <p>To facilitate communication between two VoIP clients</p> Signup and view all the answers

    What is the purpose of the OK response in SIP communication?

    <p>To acknowledge a successful registration</p> Signup and view all the answers

    What is the first step in the VoIP communication process?

    <p>Registration to the PBX</p> Signup and view all the answers

    What is the purpose of SIP responses in VoIP communication?

    <p>To send a response to a SIP request</p> Signup and view all the answers

    What is the role of SIP requests in VoIP communication?

    <p>To initiate communication with the PBX</p> Signup and view all the answers

    What is the main function of a Media Gateway in a VoIP network?

    <p>To connect different physical networks to provide end-to-end connectivity</p> Signup and view all the answers

    What is the primary function of an Analog Terminal Adapter (ATA)?

    <p>To translate data between analog and digital communication</p> Signup and view all the answers

    What is the main difference between a hard phone and a softphone?

    <p>Hard phones are traditional telephone devices, while softphones are software applications</p> Signup and view all the answers

    What is the primary function of a call agent in VoIP technology?

    <p>To route calls and manage network signaling</p> Signup and view all the answers

    What is the main function of a soft switch in VoIP technology?

    <p>To route calls and manage network signaling</p> Signup and view all the answers

    What is the primary function of a softphone?

    <p>To provide a software-based telephone solution for VoIP communication</p> Signup and view all the answers

    What is the purpose of an ATA's two ports?

    <p>One port for telephone connection and one port for LAN connection</p> Signup and view all the answers

    What is the primary function of VoIP technology?

    <p>To enable voice communication over internet protocol</p> Signup and view all the answers

    What is the primary function of an Analog Terminal Adapter (ATA)?

    <p>To enable VoIP communication on analog phones</p> Signup and view all the answers

    What is the main goal of a signaling gateway in VoIP communication?

    <p>To implement the difference between VoIP and PSTN signaling</p> Signup and view all the answers

    What is the primary function of a VoIP trunk gateway?

    <p>To facilitate the use of POTS equipment with a VoIP network</p> Signup and view all the answers

    What is the primary function of SIP in IP telephony?

    <p>To establish, modify, and terminate sessions</p> Signup and view all the answers

    What is the core IP network in VoIP communication?

    <p>A segment of the Internet that guarantees quality of service</p> Signup and view all the answers

    What is the purpose of CODECs in VoIP communication?

    <p>To digitize, compress, or convert voice data</p> Signup and view all the answers

    What is the main advantage of SIP's design in terms of mobile capability?

    <p>It allows users to use IP telephony without regard to their physical location</p> Signup and view all the answers

    What is the role of a PBX in VoIP communication?

    <p>To establish connections between end points using a SIP account</p> Signup and view all the answers

    What is the purpose of user availability in SIP?

    <p>To indicate if the user is willing to engage in communication</p> Signup and view all the answers

    What is the primary function of user capabilities in SIP?

    <p>To agree on the different features supported by the group on the call</p> Signup and view all the answers

    What is the primary function of a signaling gateway in VoIP networks?

    <p>To notify a VoIP end point that another end point requests communication</p> Signup and view all the answers

    What is the purpose of session setup in SIP?

    <p>To establish communication sessions by using session parameters</p> Signup and view all the answers

    What is the role of the core IP network in VoIP communication?

    <p>To guarantee quality of service when transporting IP packets</p> Signup and view all the answers

    What is the purpose of session management in SIP?

    <p>To modify session parameters and invoke services</p> Signup and view all the answers

    What is the primary function of SIP in the context of IP telephony?

    <p>To place, modify, and hang up calls</p> Signup and view all the answers

    What is the primary purpose of SIP requests and responses?

    <p>To communicate between clients and servers</p> Signup and view all the answers

    What is the primary purpose of SIP requests and responses in VoIP communication?

    <p>To facilitate communication between a VoIP client and the PBX</p> Signup and view all the answers

    What initiates the VoIP communication process?

    <p>The REGISTER request</p> Signup and view all the answers

    What happens to the PBX after the connection is established between two VoIP clients?

    <p>It gets out of the line and the clients communicate directly</p> Signup and view all the answers

    What is the purpose of the SIP response categories?

    <p>To categorize the types of responses sent by the PBX</p> Signup and view all the answers

    What is the role of the red arrows in Figure 65?

    <p>They represent the registration process</p> Signup and view all the answers

    What is the purpose of the OK response in SIP communication?

    <p>To acknowledge the registration request</p> Signup and view all the answers

    What is the outcome of the registration process in SIP communication?

    <p>The VoIP client receives an OK response from the PBX</p> Signup and view all the answers

    What is the role of the PBX in the VoIP communication flow?

    <p>To manage the communication session between the VoIP client and the PBX</p> Signup and view all the answers

    What is the purpose of the TRYING message in the VoIP communication process?

    <p>To notify the client that the PBX is processing the call request</p> Signup and view all the answers

    What happens when the called client accepts the call?

    <p>The PBX sends an OK message to the caller client</p> Signup and view all the answers

    What is the purpose of the green arrows in the VoIP communication figure?

    <p>To show the communication flow between the clients and the PBX</p> Signup and view all the answers

    What is the role of the PBX in the VoIP communication process?

    <p>To act as a relay between the clients</p> Signup and view all the answers

    What happens when the client sends a BYE request to the PBX?

    <p>The PBX transfers the BYE request to the other client</p> Signup and view all the answers

    What is the significance of the OK 200 message in the VoIP communication process?

    <p>It confirms a successful registration</p> Signup and view all the answers

    What is the role of the black arrow in the VoIP communication figure?

    <p>To represent the direct communication between the clients</p> Signup and view all the answers

    What is the purpose of the RING message in the VoIP communication process?

    <p>To notify the caller client that the called client is ringing</p> Signup and view all the answers

    What is the primary purpose of the SIP request-response collection?

    <p>To facilitate direct communication between two VoIP clients</p> Signup and view all the answers

    What is the first step in the VoIP communication process?

    <p>Registering with the PBX</p> Signup and view all the answers

    What happens to the PBX after the connection is established between two VoIP clients?

    <p>It gets out of the line and the two clients communicate directly</p> Signup and view all the answers

    What type of messages are sent between a VoIP client and the PBX during registration?

    <p>SIP requests and responses</p> Signup and view all the answers

    What is the role of the PBX in a VoIP communication flow?

    <p>To register VoIP clients and facilitate communication</p> Signup and view all the answers

    What is the purpose of the OK response in SIP communication?

    <p>To acknowledge successful registration</p> Signup and view all the answers

    What is the result of a successful registration to the PBX?

    <p>The client receives an OK response</p> Signup and view all the answers

    What is the purpose of the REGISTER request in SIP communication?

    <p>To register a VoIP client with the PBX</p> Signup and view all the answers

    What does the PBX send to the client after a successful registration?

    <p>An OK 200 message</p> Signup and view all the answers

    What is sent from the client to the PBX to establish a communication line?

    <p>An INVITE message</p> Signup and view all the answers

    What is the basic function of VoIP technology?

    <p>To encode voice information into a digital format</p> Signup and view all the answers

    What is the primary function of an Analog Terminal Adapter (ATA)?

    <p>To enable the use of analog telephones with VoIP networks</p> Signup and view all the answers

    What is the primary purpose of SIP in the context of IP telephony?

    <p>To manage VoIP calls and modify them in-session</p> Signup and view all the answers

    What is the role of the soft switch in VoIP technology?

    <p>To control connection between end-points where there is no end-to-end VoIP connection available</p> Signup and view all the answers

    What is sent from the called client to the PBX after receiving an INVITE message?

    <p>A TRYING response</p> Signup and view all the answers

    What is the core IP network responsible for?

    <p>Guaranteeing quality of service for voice applications</p> Signup and view all the answers

    What is the main difference between VoIP and traditional telephone communication?

    <p>VoIP uses Internet Protocol, while traditional telephone communication uses a dedicated connection</p> Signup and view all the answers

    What is the function of user availability in SIP?

    <p>To provide presence information about the user</p> Signup and view all the answers

    What happens to the communication line after the called client accepts the call?

    <p>The PBX gets out of the communication</p> Signup and view all the answers

    What is the process of encoding voice information into a digital format in VoIP?

    <p>Voice digitization</p> Signup and view all the answers

    What is the purpose of the ACK message in ending a call?

    <p>To notify the client that the remote party acknowledged the end call request</p> Signup and view all the answers

    What is the primary function of a signaling gateway?

    <p>To implement the difference between VoIP and PSTN signaling</p> Signup and view all the answers

    What is the purpose of session setup in SIP?

    <p>To establish communication session parameters</p> Signup and view all the answers

    What happens to the software tools and hardware devices after the communication line is closed?

    <p>They are stopped</p> Signup and view all the answers

    What is the primary benefit of SIP in IP telephony?

    <p>Increased mobility and flexibility</p> Signup and view all the answers

    What is the role of the media gateway in VoIP technology?

    <p>To convert digital signals to analog signals and vice versa</p> Signup and view all the answers

    What is the purpose of a VoIP trunk gateway?

    <p>To facilitate the use of POTS equipment with VoIP networks</p> Signup and view all the answers

    What is the function of SIP in user location and name translation?

    <p>To map user names to IP addresses</p> Signup and view all the answers

    What is the role of CODECs in VoIP communication?

    <p>To digitize, compress, and convert analog voice data</p> Signup and view all the answers

    What is the final step in the process of VoIP communication?

    <p>Voice decoding at the remote end</p> Signup and view all the answers

    What is the role of the PBX in a VoIP communication flow?

    <p>To route the call between clients</p> Signup and view all the answers

    What is the primary function of SIP requests and responses?

    <p>To facilitate communication between SIP clients and servers</p> Signup and view all the answers

    What is the primary function of the call agent in VoIP technology?

    <p>To manage the signaling process in VoIP communication</p> Signup and view all the answers

    What is the purpose of the TRYING message in VoIP communication?

    <p>To notify the client that the call is being processed</p> Signup and view all the answers

    What is the primary function of the PBX in VoIP communication?

    <p>To establish connections between VoIP endpoints using SIP</p> Signup and view all the answers

    What is the primary advantage of VoIP technology?

    <p>It is a cost-effective alternative to traditional telephone communication</p> Signup and view all the answers

    What is the main goal of the signaling gateway?

    <p>To implement the difference between VoIP and PSTN signaling</p> Signup and view all the answers

    What is the purpose of user capabilities in SIP?

    <p>To agree on different features supported</p> Signup and view all the answers

    What is the primary function of session management in SIP?

    <p>To modify session parameters and invoke services</p> Signup and view all the answers

    What is the role of the IP network in VoIP communication?

    <p>To route IP packets between voice applications</p> Signup and view all the answers

    What is the primary difference between VoIP and traditional telephone communication?

    <p>VoIP uses IP networks, whereas traditional telephone communication uses dedicated telephone lines</p> Signup and view all the answers

    What is the role of the soft switch in VoIP technology?

    <p>To control connection establishment between end-points</p> Signup and view all the answers

    What is the primary function of the media gateway in VoIP technology?

    <p>To convert analog signals to digital signals</p> Signup and view all the answers

    What is the process of encoding voice information into digital format in VoIP?

    <p>Voice digitization</p> Signup and view all the answers

    What is the role of the call agent in VoIP technology?

    <p>To manage calls and provide services to users</p> Signup and view all the answers

    What is the primary advantage of VoIP technology?

    <p>Cost-effectiveness and flexibility</p> Signup and view all the answers

    What is the final step in the process of VoIP communication?

    <p>Voice decoding at the remote end</p> Signup and view all the answers

    What is the primary function of VoIP technology?

    <p>To enable voice communication over IP networks</p> Signup and view all the answers

    What is the primary function of a VoIP trunk gateway?

    <p>To facilitate the use of POTS equipment with a VoIP network</p> Signup and view all the answers

    What is the main goal of a signaling gateway in VoIP communication?

    <p>To facilitate communication between VoIP and non-VoIP networks</p> Signup and view all the answers

    What is the role of CODECs in VoIP communication?

    <p>To convert analog voice signals into digital data</p> Signup and view all the answers

    What is the primary function of the core IP network in VoIP communication?

    <p>To guarantee quality of service when transporting IP packets</p> Signup and view all the answers

    What is the primary function of an Analog Terminal Adapter (ATA)?

    <p>To connect an analog telephone to a VoIP network</p> Signup and view all the answers

    What is the role of the signaling gateway in VoIP communication?

    <p>To notify a VoIP endpoint of an incoming call</p> Signup and view all the answers

    What is the primary function of a softphone?

    <p>To enable VoIP calls on a computer</p> Signup and view all the answers

    What is the primary function of a Media Gateway in a VoIP network?

    <p>To convert digital voice signals into analog data</p> Signup and view all the answers

    What is the purpose of the TRYING message sent by the PBX to the client?

    <p>To indicate that the PBX is processing the INVITE message</p> Signup and view all the answers

    What happens when the called client accepts the call?

    <p>The called client sends an OK message to the PBX</p> Signup and view all the answers

    What is the role of the PBX in establishing a communication line?

    <p>To forward the INVITE message to the called client</p> Signup and view all the answers

    What is the purpose of the ACK message in ending a call?

    <p>To notify the client that the remote party acknowledged the end call request</p> Signup and view all the answers

    What happens to the communication flow after the connection is established?

    <p>The communication flow is established directly between the two clients</p> Signup and view all the answers

    What is the purpose of the REGISTER request sent by the client?

    <p>To send SIP registration data to the PBX</p> Signup and view all the answers

    What is the role of the PBX in handling the INVITE message?

    <p>To forward the INVITE message to the called client</p> Signup and view all the answers

    What is the purpose of the OK 200 message sent by the PBX?

    <p>To complete the registration process successfully</p> Signup and view all the answers

    What is the primary function of a Media Gateway in a VoIP network?

    <p>Providing end-to-end connectivity between different physical networks</p> Signup and view all the answers

    What is the main difference between a hard phone and a softphone?

    <p>Hard phones are traditional telephone devices, while softphones are software-based</p> Signup and view all the answers

    What is the primary function of an Analog Terminal Adapter (ATA)?

    <p>Translating data between analog and digital communication</p> Signup and view all the answers

    What is the primary function of a soft switch in a VoIP network?

    <p>Routing calls and managing network signaling</p> Signup and view all the answers

    What is the main hardware component used by a softphone?

    <p>All of the above</p> Signup and view all the answers

    What is the primary function of a call agent in VoIP technology?

    <p>Routing calls and managing network signaling</p> Signup and view all the answers

    What is the purpose of an ATA's two ports?

    <p>To connect a traditional analog phone to a broadband modem</p> Signup and view all the answers

    What is the primary function of VoIP technology?

    <p>Enabling voice communication over IP networks</p> Signup and view all the answers

    What is the primary purpose of the SIP request-response collection?

    <p>To establish a connection between two clients and then allow them to communicate directly</p> Signup and view all the answers

    What is the first step in the VoIP communication process?

    <p>Registering to the PBX</p> Signup and view all the answers

    What happens to the PBX after the connection is established between two VoIP clients?

    <p>It gets out of the line and the two clients can communicate directly</p> Signup and view all the answers

    What is the purpose of the SIP responses sent by the PBX?

    <p>To respond to the SIP requests sent by the clients</p> Signup and view all the answers

    What is the main purpose of the registration process in VoIP communication?

    <p>To authenticate VoIP clients and allow them to make calls</p> Signup and view all the answers

    What is the purpose of the REGISTER request and OK response pair in VoIP communication?

    <p>To register a VoIP client to the PBX</p> Signup and view all the answers

    What is the role of the PBX in the VoIP communication flow?

    <p>To receive and respond to SIP requests and responses</p> Signup and view all the answers

    What happens after the registration process is complete in VoIP communication?

    <p>The clients can make calls to each other</p> Signup and view all the answers

    Study Notes

    SIP Requests and Responses

    • SIP requests are sent from VoIP clients to the PBX, and the PBX sends back SIP responses.
    • The connection between two clients is established by these SIP request-response collections.
    • After connection establishment, the PBX gets out of the line, and the two clients can communicate directly.

    SIP Response Categories

    • SIP responses can be sent between a VoIP client and the PBX.
    • There are different categories of SIP responses.

    SIP Communication Flow

    • The communication process involves registration to the PBX, connection establishment, and actual communication.
    • The registration is initiated by the client sending a REGISTER request, and the PBX responds with an OK message.
    • If the client needs authentication, the PBX sends back registration data, and the client sends another REGISTER request.
    • A successful registration is completed by the PBX sending an OK 200 message to the client.

    Connection Establishment

    • The communication start request is an INVITE message sent from a client to the PBX.
    • The PBX sends back a TRYING message to the client and sends the INVITE message to the other client.
    • The called client sends back a TRYING response and a RING message if the connection can be established.
    • When the called client accepts the call, an OK message is sent to the PBX, and it sends an OK response to the caller client.

    Ending a Call

    • When one of the clients wants to end the call, a BYE SIP request is sent to the PBX, which transfers it to the other endpoint.
    • The other client sends back an ACK message, which is sent to the first client, notifying that the remote party acknowledged the end call request.

    SIP Protocol

    • The Session Initiation Protocol (SIP) was designed for inviting users to Internet multicast and broadcast sessions.
    • SIP provides control over multimedia sessions, establishing, modifying, and terminating sessions.
    • In IP telephony, SIP is used to place calls, modify them, and hang up.

    Primary SIP Functions

    • User location and name translation ensure that the caller reaches the called endpoint.
    • User availability indicates if the user is willing to engage in communication.
    • Users' capabilities allow the group on the call to agree on the different features supported.
    • Session setup is used for communication session establishment using session parameters.
    • Session management is used for modifying session parameters and invoking services.

    VoIP Architecture

    • The basic architecture of VoIP technology consists of multiple components, including the soft switch, media gateway, and VoIP telephone sets.
    • The soft switch is responsible for connection control between endpoints.
    • The media gateway connects different physical networks to provide end-to-end connectivity.
    • VoIP telephone sets can be divided into softphones and hard phones.

    Analog Terminal Adapters (ATA)

    • ATAs perform analog and digital conversions between a traditional analog phone and the broadband modem.
    • ATAs allow users to use the VoIP service with an existing phone.
    • ATAs have two ports: a telephone jack (FXS port) and a LAN port.

    VoIP Basics

    • Voice over IP (VoIP) is a collection of technologies and protocols that define the basic rules for communication through the Internet Protocol.
    • VoIP works by encoding voice information into a digital format, carried across IP networks in discrete packets.
    • The VoIP communication process involves voice digitization, connection establishment, data transmission, and voice decoding at the remote end.

    VoIP (Voice over Internet Protocol)

    • VoIP allows for routing, network signaling, and billing, and is made possible by media gateways that connect different physical networks to provide end-to-end connectivity.

    Media Gateways

    • Act as network switches to create heterogeneous links between endpoints, regardless of network media.
    • Can connect VoIP circuits to PSTN circuits, allowing for VoIP use even when only one endpoint is VoIP enabled.

    VoIP Telephone Sets

    • Divided into two classes: softphones and hard phones.
    • Hard phones are traditional telephone devices capable of VoIP communication.
    • Softphones are software with telephone functions that can run on an ordinary personal computer, using main hardware devices (sound card, microphone, speaker) for communication.

    Analog Terminal Adapters (ATA)

    • Perform analog and digital conversions between traditional analog phones and broadband modems, allowing users to use VoIP service with existing phones.
    • Have two ports: a telephone jack (FXS port) and a LAN port, enabling users to plug in an analog telephone and connect to the network with an UTP cable.

    CODECs

    • Coder-decoder solutions necessary for voice digitization, compression, or conversion back to analog data.
    • Defined in standards that must be supported by VoIP communication entities like softphones, hardphones, and ATAs.

    Core IP Network

    • A segment of the Internet that guarantees quality of service when transporting streams of IP packets between voice applications.
    • Essentially an MPLS core that enables packet routing on the network.

    Signaling Gateway

    • Responsible for notifying VoIP endpoints of communication requests from other endpoints.
    • Implements VoIP signaling and PSTN notifying systems to provide communication between VoIP and non-VoIP networks.

    VoIP Trunk Gateway

    • An interface that connects Plain Old Telephone Service (POTS) equipment (like conventional phone sets and fax machines) to a voice over IP network.
    • Facilitates the connection of a Private Branch Exchange (PBX) to the PSTN.

    Session Initiation Protocol (SIP)

    • Originally designed for notifying or inviting users to Internet multicast and broadcast sessions.
    • Provides control over multimedia sessions, establishing, modifying, and terminating sessions.
    • Implemented at the application layer, it is capable of handling name mapping and redirection servers, allowing users to use IP telephony without regard to physical or network location.

    SIP Functions

    • User location and name translation
    • User availability (presence information)
    • User capabilities (agreement on supported features)
    • Session setup (establishing communication session using session parameters)
    • Session management (modifying session parameters and invoking services)

    SIP Communication Flow

    • Registration: Clients register to the PBX using REGISTER requests and OK responses.
    • Connection establishment: INVITE messages are sent from clients to the PBX, which sends TRYING responses and INVITE messages to other clients.
    • Communication: Clients communicate directly, while the PBX gets out of the communication line.
    • Call termination: BYE requests are sent from clients to the PBX, which transfers them to other endpoints, followed by ACK responses to confirm call termination.

    Voice Over IP (VOIP)

    • VOIP is a collection of technologies and protocols that define the basic rules for communication through the Internet Protocol.
    • VOIP works by encoding voice information into a digital format, which can be carried across IP networks in discrete packets.

    VOIP Architecture

    • The basic architecture for VOIP technology consists of several parts, including:
      • Softswitch: a software solution that controls connection between end-points.
      • Media Gateway: a part of the softswitch that enables a user to plug into the FXS port an analog telephone, and then attach the ATA to the network with an UTP cable.
      • Call Agent: a part of the softswitch that enables a user to establish a connection between the end-points.
      • Core IP Network: a segment of the Internet (or a special case of the Internet itself) that guarantees a quality of service when transporting a stream of IP packet between voice applications.
      • Signaling Gateway: responsible for notifying a VOIP end point that another end point requests for communication.
      • VOIP Trunk Gateway: an interface that facilitates the use of plain old telephone service (POTS) equipment, such as conventional phone sets and fax machines, with a voice over IP network.

    Session Initiation Protocol (SIP)

    • SIP is a protocol used for establishing, modifying, and terminating sessions in IP telephony.
    • The primary SIP functions are:
      • User location and name translation
      • User availability
      • User capabilities
      • Session setup
      • Session management
    • SIP requests and responses are used for communication between VOIP clients and the PBX.

    SIP Communication Flow

    • The SIP communication flow involves the following steps:
      • Registration to the PBX
      • Connection establishment
      • Actual communication
      • End of communication
    • The registration process involves a REGISTER request and an OK response pair.
    • The connection establishment process involves an INVITE message, TRYING messages, and RING messages.
    • The actual communication is made directly between the two VOIP clients.
    • The end of communication process involves a BYE SIP request and an ACK message.

    Introduction to VOIP

    • VOIP (Voice Over IP) is a collection of technologies and protocols that enable communication through the Internet Protocol.
    • VOIP works by encoding voice information into a digital format, which can be carried across IP networks in discrete packets.

    VOIP Architecture

    • The basic architecture of VOIP technology consists of various components, including soft switch, media gateway, and VoIP telephone sets.
    • Soft switch is a software solution that controls connection between end-points, and it can be divided into two parts: media gateway and call agent.
    • Media gateway is used to connect different physical networks to provide end-to-end connectivity and can also connect a VoIP circuit to a PSTN circuit.
    • Call agent is responsible for call routing, network signaling, and billing.

    VOIP Telephone Sets

    • VoIP telephone sets can be divided into two classes: softphones and hard phones.
    • Hard phones are traditional telephone devices capable of VoIP communication.
    • Softphones are software with all telephone functions that can run on an ordinary personal computer and use the main hardware devices for realizing the communication.

    Analog Terminal Adapters (ATA)

    • ATAs perform analog and digital conversions between a traditional analog phone and the broadband modem, allowing users to use the VOIP service with an existing phone.
    • ATAs typically have two ports: a telephone jack (FXS port) and a LAN port.
    • Codecs (coder-decoder solutions) are required for voice digitization, compression, or conversion back to analog data.

    Core IP Network

    • The core IP network is a segment of the Internet that guarantees a quality of service when transporting a stream of IP packets between voice applications.
    • The core IP network is basically the MPLS core, which enables the routing of packets on the network.

    Signaling Gateway

    • The signaling gateway is responsible for notifying a VoIP end-point that another end-point requests for communication.
    • The main goal of the signaling gateway is to implement the difference between the VoIP signaling and the PSTN notifying system.

    VoIP Trunk Gateway

    • A VoIP trunk gateway is an interface that facilitates the use of plain old telephone service (POTS) equipment, such as conventional phone sets and fax machines, with a voice over IP network.
    • The VoIP trunk gateway is used for connecting the Private Branch Exchange (PBX) to the PSTN.

    SIP (Session Initiation Protocol)

    • SIP is a protocol used for establishing and terminating communication sessions between VoIP clients.
    • SIP requests are sent to the PBX from the VoIP clients, and the PBX sends back SIP responses in return or vice versa.
    • The connection between two clients is established by these SIP request-response collections, and after the connection is established, the PBX gets out of the line and the two clients can communicate directly.

    SIP Communication Flow

    • The SIP communication flow involves registration, connection establishment, and actual communication.
    • The first step of the communication is the registration to the PBX, which involves a REGISTER request and an OK response pair.
    • A successful registration is always completed by the PBX sending an OK 200 message to the client.
    • When both clients are registered, they can request for communication line establishment, which involves INVITE messages, TRYING responses, and RING messages.
    • When the called client accepts the call, an OK message is sent to the PBX, and it also sends an OK response to the caller client.
    • At this point, the connection between the two clients is established, and the PBX gets out of the communication.
    • The communication itself is made directly between the two VoIP clients, and it can be ended by sending a BYE SIP request.

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    Related Documents

    W4_JTO_Ph2_Datacom_IT-part-12.pdf

    Description

    Understand the mechanism of SIP requests and responses in VoIP, including how connections are established between clients and the PBX.

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