Classroom Companion: Business

3.1 
 Dedicated Networks
Historically, separate and dedicated communication networks were designed for 
carrying different telecommunication services. This means that a separate and ded-
icated physical infrastructure was constructed for each digital service offered. 
Hence, the provision of a new service (e.g., TV or radio) demanded the building of 
a completely new physical infrastructure, in which most cases had huge up-front 
costs. Examples of such dedicated network include:
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Public switched telephone network (PSTN) for telephone services. This net-
work also supports the facsimile service and several value added services, for 
example, premium rate calls, free-phone, televoting, and particular call han-
dling services such as time-dependent call routing.
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Public mobile networks for voice, data, and messaging services (SMS and 
MMS).
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Wireless one-way networks for audio and television broadcasting.
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Cable and satellite networks for audio and television broadcasting.
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Telex network for low-speed text transmission.
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Satellite access networks for communication with ships, aircraft, land mobile 
terminals, and remote areas (e.g., Inmarsat, Skyphone, and Iridium).
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Dedicated data networks for various digital data services, for example, the X.25 
network and the Internet.
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Dedicated networks for search, rescue, and distress communications.
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Fixed and wireless telegraphy networks using the International Morse Code, 
for example, used for distress communications with ships and for railway 
signaling.
All these networks, except the telegraphy networks, the telex network, and some 
early data networks (X.25), are still in operation today. Telegraphy based on the 
International Morse Code was standardized for continental Europe in 1851. Other 
countries, e.g., the UK and USA, used other incompatible methods. In 1865, the 
International Telegraph Union—now the International Telecommunications 
Union (ITU)—was established for the purpose of technical, operational, and com-
mercial standardization of a single international telegraphy service to be used in all