a logical chain of events would be :
1- high drop call %, subscribers are getting cut while calling someone or getting called.
2- subscribers are trying to re-establish the call, all at about the same time
3- due to simultaneous trials, there is a PCH (paging channel) high load.
Of course, it’s just an assumption.
Otherwise, can you find out the cause of call drop rate (bad radio, interference, coverage, during HO, due to hardware failures, due to transmissions…?), what is the average call duration ?
what is the SDCCH drop %
what is the RACH load, the AGCH load (and requests ?)
is the phenomenom occuring on all cells of a BSC ?
alls cell of a LAC ?
just a few cells in a cluster ?
random cell ?
check your combined BCCH settings also..
from NSS point of view, i’m not an expert, so i’ll just help you to clear out a possible radio issue.