I.Introduction

II.The Historic Telephone Network

A.Network Operations and Design of the Historic Telephone Network
B.Traffic and Cost Characteristics of the Historic Telephone Network
C.Implications of PSTN Evolution

III.The Present Telephone Network

A.Traffic and Cost Characteristics the Present Telephone Network
B.Implications of the Modern PSTN

IV.The Internet

V.Future Networks

A.Traffic and Cost Characteristics
B.Implications of Future Networks

VI.Trends and Consequences

A.Trends
B.Consequences

VII.Conclusion