ETSI EN 300 968-1999 Digital Cellular Telecommunications System (Phase 2+); Half Rate Speech; Test Sequences for the GSM Half Rate Speech Codec GSM 06.07 Version 6.0.1 Release 1997
2000ETSI EN 300 968:2000 Digital Cellular Telecommunications System (Phase 2+); Half Rate Speech; Test Sequences for the GSM Half Rate Speech Codec (GSM 06.07 Version 8.0.1 Release 1999)
1999ETSI EN 300 968-1999 Digital Cellular Telecommunications System (Phase 2+); Half Rate Speech; Test Sequences for the GSM Half Rate Speech Codec GSM 06.07 Version 6.0.1 Release 1997