In ALU system, if a MS is AMR and the AMR feature is enabled, the call are always initiated in AMR. It is going to be AMR FR if cell is low loaded and AMR HR if cell is loaded.
The AMR FR codec list contains a codec at 12.2 kb/s, which is equivalent to the EFR. So AMR FR should provide exactly the same quality as EFR.
The Dark knight : which system are you using ?
Is it possible that TEMS does a mistake ?
Within the same cell, do you see that the codec is changing AMR -> EFR -> AMR ? Normally, that shouldn’t be possible.
The codec could change from AMR to EFR only during an intercell HO, if the target cell does not support AMR.