Telephone systems are considered to be most important low voltage system in regards to modern business operations. Telephone systems are used to form a communication link that spans nationally, globally, and within a company. They are used to place customer orders, provide access to remote fire alarm and security systems monitoring, and communicate internally and externally. Today's telephone systems range from a simple single line telephone to a global hybrid Voice over Internet Protocol (VoIP) network. Modern telephony no longer depends on the traditional telephone company for service, alternatives such as internet based telephony (Voice over Internet Protocol, cable companies, and cellular service are popular alternatives to the traditional telephone company line.

Unit Objectives

• Describe the basic components and operation of the Public Switched Network
• Examine the common communications modulation techniques
• Describe the common telecommunications services available
• Undertand telephone system wiring schemes
• Describe the different of types of customer provided telephone systems.
• Summarize the appliactions and operations of DSL, VoIP, T-1, and POTS