i dont know much about 3G and stuffs but what i can say is that mobile (i mean Nokia 3G handsets like 5800XM C6 X6 etc) wont give u great speeds on 3G coz their parameters are not equal to the data card.... in mobile maximum possible downlink speed is 384 kbps ..... same for datacard also... but what u get with datacard is HSDPA .. which actually gives u the great speed.... Nokia mobile doesnt have HSDPA.... thats why u wont get good speeds... just try ur same sim on a iPAD and see the difference in speed.... iPAD wud give u same speed as a datacard.... its better to use Datacard if ur using it for heavy downloads and video streaming (HD categorically) .... if i am wrong sumwhr plz do correct me.... as i said i am not much sound abt 3G .