Category: 01 – VOIP standards

  • Benefits of VoIP

    Lower operational cost – single infrastructure, free additional features (caller ID & conference call). Flexibility – more than one call over single broadband connection. Security – encrypt/authenticate IP stream. Integration – video conversation, data file exchange & audio conference.  

  • Corporate Users

    Many large companies have extensive data communications networks internally and across sites. No need to spend extra for voice services, use existing network for VoIP services. Advantages: Migrating from copper-wire to VoIP over data network Better use of bandwidth Lower cost – no duplicating services Unified communication systems – single infrastructure to manage Dual-mode phones…

  • Telecommunication Providers

    “IP Backhaul” – providing links between switching stations (exchanges) and connecting between providers. Some providers rolling out VoIP in place of standard telephony service.

  • Consumer Market

    Available since 2004. Delivered by existing broadband connection. Behaves much like standard Public Switched Telephone Network (PSTN). Requires equipment: Dedicated VoIP phone, or Adaptor for standard analog phone, or Software and headset/web cam Benefit for home users is ability to make free phone calls, especially when making long distance calls. Most common provider is Skype.

  • SIP Messages

    SIP protocol defines several messages: INVITE: inviting user to call BYE: terminating connection between two end points ACK: reliable exchange of invitation messages OPTIONS: get information about capabilities of call REGISTER: passes user location information to SIP registration server CANCEL: terminates search for user

  • SIP Components

    User Agents: End system acting on behalf of user e.g. client & server. Initiates SIP request & server receives requests and returns responses on behalf of user. Network Servers: Three types available: Registration server – receives client location updates. Proxy server – forwards receiving request to next-hop server. Redirect server – determines next-hop server, returns…

  • SIP Functions

    SIP has following functions: User Location: determination of end system to use for communications Call Setup: ringing & establishing call parameters by both called and calling parties User Availability: determination of willingness of called party to engage in communications User Capabilities: determination of media and media parameters to use Call Handling: transfer & termination of…

  • Session Initiation Protocol (SIP)

    Distributed architecture for creating, modifying and terminating sessions with one or more participants. Controls communications sessions. Standardised under IETF. Covers video conferencing, audio conferencing and one-to-one telephone calls. Stack independent, usually run over TCP or UDP. Uses request/response model similar to HTTP – client sends a request and gets a response from server. Requests/responses in…

  • H.323

    ITU-T’s (International Telecommunications Union) standard – vendors need to comply to supply VoIP. Encompasses point to point communications & multipoint conferences. Consists of four components: Terminals Endpoint host systems providing real time, two way comms. Can communicate with another H.323 terminal, H.323 gateway or MCU. Gateways Endpoint providing communication between terminal or another gateway. Translates…

  • Current VoIP Standard

    Carrying mechanism is Internet Protocol (IP). Protocol issues around establishing and managing connection. Different protocols available for VoIP.