Welocome back! We do not have Abis Optmizer.
I am not aware of switcable time slot. Is it in Ericsson system??? One more thing to add to it is SPDCH isn yet different optional feature of Ericsson. If u activate SPDCH data is given first priority, and if at all the data time slot is free, then it can be preempted by voice. voice cannot be preempted unless data TS is free. But in flexi Abis, voice is given first priority. also, we need not allocate any TS.
All these are theorotical. am not having SPDCH to experiment.