ETSI GSM 06.01-1993 European Digital Cellular Telecommunication System (Phase 2); Speech Processing Functions: General Description (ETS 300 580-1 Version 4.0.5)
1993ETSI GSM 06.01-1993 European Digital Cellular Telecommunication System (Phase 2); Speech Processing Functions: General Description (ETS 300 580-1 Version 4.0.5)
1992ETSI GSM 06.01-1992 European Digital Cellular Telecommunication System (Phase 1); Speech Processing Functions: General Description