I have problem of high SDCCH Drop at BSC Nokia too. The condition was after swapping out our old BSS to Nokia BSS, SDCCH Drop was increased from 0% to 5%, and it happened almost for all the BTS, and the other indicators were fine. But the problem wasn’t appeared when the BSC are connected to MSC Ericsson. Fyi, my network adapted multiply vendors for MSC such as Alcatel, Siemens, even Nokia itself. Are there any parameters that should be tunned that matched with MSC Ericsson but not to the others ??