there is no solution.
Statistic of your BTS is correct, everything is correct, you have changed every card (BOIA, FXC, 13Mhz is ok, …) ….and you have still this alarm.
I have a same problem and now i don’t care because my site is working and all good work.
I think that problem is quality of PCM 2Mbits. But where and why? i don’t know.
check your ET with => ZYMO:ETxx;