Broadband Telecommunications Technologies and Management

3Voice Communications

Preview Questions

• How is voice communicated electrically?
• What is the bandwidth of human voice? Why does it matter?
• How are multiple telephone calls carried over the same physical link?
• How can telephone networks be dimensioned?
• How did telephone operator businesses monopolies emerge and how was competition introduced?

Learning Objectives

• History of voice communications and emergence of telephone operator businesses
• Principles of voice communications
• Analogue modulation and signal multiplexing
• Statistical multiplexing and network dimensioning
• Regulation and deregulation of telecom operation industry

Historical Note

The word telephone was coined by Gottfried Huth in 1796 to describe his invention of a network of mouth trumpets or speaking tubes that could ‘pass messages from tower to tower’ [1]. The distance over which such telephony could be carried out was clearly limited by the power of the ‘loudspeaker’ trumpets. However this was only 2 years after the first official Chappe telegraph message, and before the widespread use of electricity and understanding of electromagnetic waves. The mere fact that telephony was considered is noteworthy.

A system (pictured)¹ for transmitting sound using electrical signals was first demonstrated by Johann Philipp Reis, a German scientist, ...