The basics of telephony interfaces and telephony wiring??”FXO, FXS, BRI,
and PRI.
Once you have acquired the above mentioned knowledge, continue your journey
into the world of Asterisk??”the open-source PBX, and AsteriskNOW??”the Asterisk
appliance distribution.
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An Introduction to Telephony and Asterisk
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The Basics of Traditional Telephony
One of the most common terms in telephony is the exchange or switch, which
refers to the actual device or mechanism that connects the parties who wish to
converse over a telephone line. In most cases, the exchanges are located in a
centralized location, interconnected with hundreds, sometimes thousands of end
terminals (telephones). Exchanges are then interconnected among themselves via
connecting trunks. Trunks are connections capable of carrying multiple phone calls
concurrently, thus enabling calls to traverse among exchanges.
One might ask, "If there are thousands of end terminals and a multitude of exchanges
within a network, how does a call know where to ring?" To understand this, take a
deeper look into the term circuit switching.
Circuit Switching
Circuit switching refers to the methodology of interconnecting end terminals before
actual information can traverse between them.
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