I looked up at the starry night and I saw the pix-signal :))
There is no correlation between T3212 & call drops or ho… None at all… The T3212 would only impact SDCCH traffic (sd drops, sd duration, etc) and perhaps (in worst case) some obscure NSS indicators about paging failures or call setup failures.
It cannot impact a MS which is already in dedicated mode.
Perhaps evil forces are at work here ?
Have you tried putting the t3212 back to its previous value ? Are the KPIs better after that ?
If it were my network, I would strongly suspect that something else was changed too… at the same time the t3212 was changed 😉