in a cell, let’s assume :
one week without AMR : “X” call drops, “Y” disconnections
next week with AMR : “X+d” call drops, “Y-d” disconnections
people prefers to disconnect a call as soon as there is no more voice (case of non AMR calls under poor radio conditions)
when you activate AMR, the ppl will feel the voice is fine, but the BSS feels otherwise, because the SACCH are lost.
if you still don’t understand, i’m not sure i can do anything more 🙂 Read few more times…