30 minutes is insane…
A network with a T3212 set at 30 minutes would just implode under the gigantic load.
I’m pretty sure Nokia’s default is 3 hours 🙂
It’s very funny : you just decreased the number of SD drops, probably reduced the SD congestion and the VLR/HLR load, and yet you are not happy. Sometimes it is dangerous to focus only on the corporate KPIs 🙂
If you want to decrease the SDCCH drop rate, you’ll have to focus on interference, coverage, path balance, … you’ll probably have to work on a cell per cell basis. Extract the worst cells (highest number of drops), and see what is the main SDCCH usage, see why it drops, etc…