MAS.632 Conversational Computer Systems - MIT OpenCourseWare

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computer interface
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Tephn and Computers
Figure 11.10. A distributed architecture with a telephone peripheral on
each workstation.
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switch
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local area network, sending requests and receiving events (such as notification of
an incoming call) from the server. In this centralized architecture, application
requests are translated into messages for the server and sent over the computer
network; the server, in turn, translates these into commands to its local hardware
and thence onto the telephone network. The centralized approach requires that
one computer interact with many telephone lines so that a single server can act
on behalf of a number of clients. This can be accomplished in several ways: each
line can be connected to the server or the server can communicate directly with
the telephone switch.
With analog telephony, each line has its own independent circuit for signaling
and voice. A multiline analog telephone or key set has a pair of line wires for each
line and selects between them with buttons. Similarly, interfacing a computer to
multiple analog lines requires the use of one telephone line interface board per
line. A single board can be made to handle multiple lines by replicating the interface
circuits, which reduces the per-line expense; consequently, such boards are
often used in voice mail systems, serving four to sixteen lines per board.
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