DIN ETS 300549:2001 Digital cellular telecommunications system (Phase 2) - Unstructured Supplementary Service Data (USSD) - Stage 2 (Endorsement of the English version ETS 300549:1996-06 as German standard)
2001DIN ETS 300549:2001-04 Digital cellular telecommunications system (Phase 2) - Unstructured Supplementary Service Data (USSD) - Stage 2 (Endorsement of the English version ETS 300549:1996-06 as German standard) / Note: Endorsement notice
2001DIN ETS 300549:2001 Digital cellular telecommunications system (Phase 2) - Unstructured Supplementary Service Data (USSD) - Stage 2 (Endorsement of the English version ETS 300549:1996-06 as German standard)