AT&T Worldwide Intelligent Network: reliability, restoration, and special survivability initiatives

The AT&T Worldwide Intelligent Network is the largest in the world and contains approximately 2.75 billion circuit miles of transmission facilities; more than 130 digital switches; the world´s largest data packet switched network used for call set up and advanced services; and the most advanced network management tools in existence. The basic architecture for the switched portion of the network is comprised of a number of various hardware and software components. AT&T has based its planning on basic principles which are aimed at assuring the reliability of its network as well as the ability to promptly restore traffic for its customers in the event of an outage. These principles fall into four categories: prevention, flexible switching capabilities, facilities restoration, and repair of damaged facilities and/or equipment