Switching to VoIP

This is the Title of the Book, eMatter Edition

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Chapter 4: Circuit-Switched Telephony

The FCC communicates with these bodies in order to make sure that the PSTN

serves the public interest and is beneficial to consumers, while allowing an atmo-

sphere of economic growth that is conducive to the involvement of private business.

Though the PSTN’s technologies are governed by the ITU, an international body,

state governments and the FCC maintain lawful use of the PSTN in the U.S.A.

The International Telecommunications Union

The ITU-T (Telecommunications Standardization Sector) is the ITU’s working group

charged with governance of global standards for telephony practices and protocols.

The ITU-T publishes recommendations that dictate the technologies used in public

and private telephony. While the ITU-T has published some packet-based recom-

mendations, like H.323, the majority of its work has focused on legacy, circuit-

switched telephony networking. Its standards are categorized into groups by func-

tion. Each group is abbreviated using a letter. Here are the most relevant ones:

E Overall network operation, telephone service, service operation, and user interface

G Transmission systems and media

H Audiovisual and multimedia systems

I Integrated services digital network (ISDN)

O Specifications of measuring equipment

P Telephone transmission ...