tailieunhanh - Modern Telecommunications P2

Where early switches and computers tended to be hardwired, modern switches and computers are both stored-program machines and very flexible. The switch uses a stored-program model to handle call routing operations. The computer uses a variety of stored programs to support end-user applications. Both depend on a data communications infrastructure to exchange control information. Finally, the telephone network is rapidly converging to the digital communications model, which computers have used almost from the outset | electromechanical monstrous in size and highly rigid in their design. Over the years however both computers and switches became entirely electronic and based on solid-state technologies. Where early switches and computers tended to be hardwired modern switches and computers are both stored-program machines and very flexible. The switch uses a stored-program model to handle call routing operations. The computer uses a variety of stored programs to support end-user applications. Both depend on a data communications infrastructure to exchange control information. Finally the telephone network is rapidly converging to the digital communications model which computers have used almost from the outset. Telephone switches have become specialized computers designed to provide a switching function and exchanging information via a complex digital data communications infrastructure. The third major part of the definition functional integration requires a brief sidetrack to examine the anatomy of a phone call. A phone call can be divided into two logical activities commonly referred to as call control and media processing. Call control is concerned with originating maintaining and terminating a call. It includes activities like going off-hook dialing the phone routing a call through a network and terminating a call. Media processing is concerned with the purpose of the phone call. It deals with the type of information being conveyed across the call and the format in which that information is presented. Functional integration means the computer and switch collaborate in call control and or media processing operations. They may actually interchange functions to meet the needs of an application. Data stored in the computer might be useful for routing incoming and or outgoing calls. Perhaps the simplest example is an autocall application where the user can click on a name stored in a local application and the computer retrieves the associated phone number and dials the call .