ITU-T E.501-1997
网路话务估计 E系列:全面网络操作 电话服务 服务操作和人员因素 网络管理和交通工程 交通的测量
Estimation of Traffic Offered in the Network - Series E: Overall Network Operation Telephone Service Service Operation and Human Factors Quality of Service Network Management and Traffic Engineering - Traffic Engineering - Measurement and Recording of Tra