An adequate picture of the level of quality of service (QOS) in the network can be defined by a set of parameters which are measured, registered and data processed.
ITU-T E.420-1993 Referenced Document
ITU-T E.125 Inquiries Among Users of the International Telephone Service*， 1998-01-01 Update
ITU-T E.420 CHECKING THE QUALITY OF THE INTERNATIONAL TELEPHONE SERVICE – GENERAL CONSIDERATIONS
ITU-T E.425 Internal Automatic Observations Series E: Overall Network Operation Telephone Service Service Operation and Human Factors Network Management - Checking the Quality of the International Phone Service Study Group 2*， 2002-03-01 Update
ITU-T E.426 General Guide to the Percentage of Effective Attempts Which Should Be Observed for International Telephone Calls - Telephone Network and ISDN Quality of Service Network Management and Traffic Engineering (Study Group II) 3 pp
ITU-T M.1230 Method to Improve the Management of Operations and Maintenance Processes in the International Telephone Network - Series M: Maintenance: International Transmission Systems Telephone Circuits Telegraphy Facsimile and Leased Circuits; International Public T*， 1996-05-01 Update
ITU-T M.710 General Maintenance Organization for the International Automatic and Semi-Automatic Telephone Service - General Maintenance Principles - Maintenance of International Transmission Systems and Telephone Circuits (Study Group IV) 8 pp
ITU-T M.711 Escalation Procedure - General Maintenance Principles - Maintenance of International Transmission Systems and Telephone Circuits (Study Group IV) 1 pp
ITU-T E.420-1993 history
1993ITU-T E.420-1993 CHECKING THE QUALITY OF THE INTERNATIONAL TELEPHONE SERVICE – GENERAL CONSIDERATIONS