Hi , my application does not use any data download from server. but whenever i start the application the "up/down arrows in the upper right in blackberry" shows up for a moment. can any body confirm why this can happen and let me know whether there is any chance of UP/DOWN arrows appearing for any other scenario besides data download?

those arrows means its sending and receiving something from the wireless network. Those arrows appear everytime you are on a call, send a SMS, use data... anything to do with the wireless network those arrows will appear

when i test it in blackberry emulator also.. its showing this arrows.. So is it just a simulation of network thats causing the arrows to appear?? cus in emulator i cant make a call or send a SMS.

Yes. it sounds normal to me.