I have notice that when i installed Facebook application , i get notification from it when there's new messages coming in WITHOUT WIFI ON !!

I guess its because of the Mobile Network -> Packet Data and Roaming Data ..

But turning off Packet Data will result in turning off 3G/3.5G , right ??

Is there any way to solve this problem ??
-No data transfer from Facebook or any other application (Only when WIFI is On , then data transfer approve)
-3G/3.5G still activate ..
-MMS still activate