ITU-T D.220-1991 通过综合业务数字网(ISDN)所提供的国际电路模式所需的承载业务的计费和结算原则(研究组3)5 p
Charging and Accounting Principles to Be Applied to International Circuit-Mode Demand Bearer Services Provided over the Integrated Services Digital Network (ISDN) (Study Group III) 5 pp
The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of
the Intemational Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations o