Abdel, your network should have a hierarchical synchronisation plan, for synch of the MSC, down to the BTS’s as a minimum, this will reduce your slip alarms, and probably show KPI improvements as well. GPS synchronisation of the BTS’s allows synchronised handovers to be configured to adjacent cells not sharing the same transmission/common local clock. It removes any timing differences due to transmission delays I believe. We did try it here for a little while but saw no improvements, however the BSC’s and MSC’s in our network are synchronised to GPS as a primary clock source.