Introduction - If you have any usage issues, please Google them yourself
ETSI EN 300 723 V8.1.1 (2000-11)
Digital cellular telecommunications system (Phase 2+) (GSM)
Enhanced Full Rate (EFR) speech processing functions
General description (GSM 06.51 version 8.1.1 Release 1999)
en_300723v080101p.pdf(官方文档)
ETSI EN 300 726 V8.0.1 (2000-11)
Digital cellular telecommunications system (Phase 2+) (GSM)
Enhanced Full Rate (EFR) speech transcoding (GSM 06.60 version 8.0.1 Release 1999)
en_300726v080001p.pdf(官方文档)