Hi sheldon,
ya prabeen is right.u do not need to define any 16 kbps timeslot for opdch and if its 100% and there is need of gprs traffic and idle tch will be there then it will go on
while in egprs u can define fpdch+spdch+ switchable edge timeslot.
for this switchable timeslot we need to define 64 kbps on abis but u can this timeslor for voice when there is less edge traffic.
sheldom remember my earlier post in which i asked abt 30 edge timeslot in that there was 16 fpdch + spdch and remaining 14 were switchable fixed on abis(64 kbps) but on radio level they can also fofr voice