ITU-T Rec. D.35 (11/1988) GENERAL CHARGING AND ACCOUNTING PRINCIPLES IN THE INTERNATIONAL PUBLIC INTERPERSONAL MESSAGING (IPM) SERVICE
Preamble
1 Collection charges
1.1 Basic IPM service (as defined in Recommendation F.400)
1.2 IPM service optional user facilities (as defined in Recommendation F.400)
2 International accounting
2.1 Basic IPM service
2.2 IPM service optional user facilities