Reference
[1]3GPP 24.008
[2]3GPP 48.008
[3]3GPP 26.103 Speech codec list for GSM and UMTS
[4]3GPP 25.413 UTRAN Iu interface RANAP signalling
[5]ITU-T Q.765.5
[6]ITU-T G.722 == UMTS_AMR
[7]ITU-T G.723.1 == UMTS_AMR2
2G
For 2G GSM, there is no concept of codec and only concepts of speech versions exist. The speech versions are carried in "BearerCapacity IE" and "Channel Type IE". The normally applied speech versions are followed:
GSM speech full rate version 1
GSM speech full rate version 2
GSM speech full rate version 3
GSM speech half rate version 1
GSM speech half rate version 2
GSM speech half rate version 3
'GSM speech full rate version 2' is also referred as EFR(Enhanced Full Rate).
'The GSM speech full rate version 3' is also referred as the adaptive multi-rate full rate speech version 1(FR_AMR).
"The GSM speech half rate version 3' is also referred as the adaptive multi-rate half rate speech version 1(HR_AMR).
3G
For 3G UMTS, concept of codec is introduced. "Supported Codec List IE(SCL)" is added to SETUP message. The codecs in SCL are followed[3]:
GSM Full Rate Codec Type (GSM FR)
GSM Half Rate Codec Type (GSM HR)
GSM Enhanced Full Rate Codec Type (GSM EFR)
Four Adaptive Multi-Rate Codec Types (FR AMR, HR AMR, UMTS AMR, UMTS AMR2)
TDMA Enhanced Full Rate Codec Type (TDMA EFR)
PDC Enhanced Full Rate Codec Type (PDC_EFR)
GSM Full Rate Codec Type (GSM FR) == GSM speech full rate version 1
GSM Half Rate Codec Type (GSM HR) == GSM speech half rate version 1
GSM Enhanced Full Rate Codec Type (GSM EFR) == GSM speech full rate version 2
FR AMR == GSM speech full rate version 3
HR AMR == GSM speech half rate version 3