Stage 3 Description for Numbering Identification Supplementary Services Using SS No. 7: Direct-Dialling-in (DDI) - Series Q: Switching and Signalling; Specifications of Signalling System No. 7 - ISDN Supplementary Services Study Group 11; 15 pp [Supersede
ïïU-T Recommendation 4.731.1 was revised by ITU-T Study Group 11 (1993-1996) and was
approved under the WTSC Resolution No. 1 procedure on the 9th of July 1996