to katik:
FR – full rate
EFR – enhansed full rate
it is a 13 k/s codecs which used in GSM, I didn’t remember exact specification for them, but you can find them on http://www.etsi.org
quality of sound at EFR is better then at FR, the voice at EFR is more “live”, more “open” … I can’t explaine the difference, you have to hear it to understand…
alex
http://www.dx200.biz