Both technology (equipment and software) suppliers and service providers tend to specialize in one or two of these layers, each of which seeks to serve all applications and all media. As a consequence, creating a new application may require the participation and cooperation of a set of complementary layered capabilities. This structure results in a horizontal industry structure, quite distinct from the vertically integrated industry structure of the Bell System era. that support communication at a distance.
The range of telecommunications applications is broad and includes telephony and video conferencing, facsimile, broadcast and interactive television, instant messaging, e-mail, distributed collaboration, a host of Web- and Internet-based communication, and data transmission. 3 Of course many if not most software applications communicate across the network in some fashion, even if it is for almost incidental purposes such as connecting to a license server or downloading updates. Deciding what is and is not telecommunications is always a judgment call. Applications of information technology range from those involving almost no communication at all (word processing) to simple voice communications (telephony in its purest and simplest form), with many gradations in between.
As supported by the horizontally homogeneous layered infrastructure, applications of various sorts increasingly incorporate telecommunications as only one capability among many. For example telephony, as it evolves into the Internet world, is beginning to offer a host of new data-based features and integrates other elements of collaboration (eg, visual material or tools for collaborative authoring). Another important trend is machine-to-machine communication at a distance, and so it cannot be assumed that telecommunications applications exclusively involve people.
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