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. Continue Reading
Learning
Learning and development resources and notes.
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 Continue Reading
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 Continue Reading
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 Continue Reading
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 Continue Reading
Current VoIP Standard
Carrying mechanism is Internet Protocol (IP). Protocol issues around establishing and managing connection. Different protocols available for VoIP.
Information Technology Infrastructure Library (ITIL)
Independent set of standards and practices for running I.T department. Details processes that should exist and what best practise is. Provides standard for I.T. departments to use for benchmarking and measuring their performance. ITIL areas cover: Financial management for I.T. department Service design Service level management Availability management Capacity management Continue Reading
Planning Tools
Tools used to support I.T. department planning, range from Excel to Project or even more specialised products. Choice depends on size and complexity of project. MS Project can link several projects together under one steering project facilitating project management. Many tools can also provide costings for the projects to assist Continue Reading
Software Management Tools
Many tools available to help manage I.T. departments, both simple and complex. Can be stand alone for specific functions or fully integrated systems covering areas such as: Code repository Asset repository Help desk Data models repository Software analysis and design repositories