ETSI TS 123 090
ETSI TS 123 090
Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Unstructured Supplementary Service Data (USSD) - Stage 2 (3G TS 23.090 version 3.1.0 Release 1999)
standard published 01/01/2000 by European Telecommunications Standards Institute