Modern international networks have evolved from point-to-point networks with single routes interconnecting ROAs of different countries to more complex networks with multiple routes between countries. The number of interconnections between countries has increased due to growth in the number of ROAs, the ability to transit calls through intermediate countries, and an increase in the flexibility in routing mechanisms supported by modern switching equipment. This is illustrated by the following figure where we see three routes between two countries. In this example, two routes are direct routes, which may use the same or different technology, and the third is a non-direct or transit route.
ITU-T E.437 SPANISH-1999 Referenced Document
ITU-T E.425-1998 Internal Automatic Observations - Series E: Overall Network Operation@ Telephone Service@ Service Operation and Human Factors - Quality of Service@ Network Management and Traffic Engineering - Network Management - Checking the Quality of the International
ITU-T E.431-1992 Service Quality Assessment for Connection Set-up and Release Delays (Study Group II) 6 pp
ITU-T E.450-1998 Facsimile Quality of Service on Public Networks - General Aspects - Series E: Overall Network Operation Telephone Service Service Operation and Human Factors - Quality of Service Network Management and Traffic Engineering - Network Management - Checking t