The worldwide nature of the international telephone network, spanning as it does all possible time zones, has stimulated studies of the traffic streams between countries in different relative time locations. These studies have led to the development of standardized 24-hour traffic profiles which, theoretically based and verified by measurements, would be useful for engineering purposes.
ITU-T E.523-1993 Referenced Document
ITU-T E.523 STANDARD TRAFFIC PROFILES FOR INTERNATIONAL TRAFFIC STREAMS
ITU-T E.523-1993 history
1993ITU-T E.523-1993 STANDARD TRAFFIC PROFILES FOR INTERNATIONAL TRAFFIC STREAMS
1988ITU-T E.523-1988 Standard traffic profiles for international traffic streams