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Cisco Self-Study: Building Cisco Metro Optical Networks (METRO) by Dennis Hartmann, Dave Warren

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Chapter 2. Voice History

This chapter covers the following topics:

  • A short history of voice and data transmission

  • The digital hierarchy

  • Developing a digital hierarchy outside the United States

  • Expanding the digital hierarchy

This chapter examines the history of the telco network with voice. You examine the original digital hierarchy scheme, which provides an overview of the speeds normally used to transport traffic over copper. You discover the multiplexing functionality in the telco world, and you examine the differences between analog and digital signaling.

A Short History of Voice and Data Transmission

When the telephone was first introduced in 1876, Alexander Graham Bell used sound waves to create an electrical current that was transported across ...

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