it is very useful i have been using it since i came here in qatar.. you dont need to buy modem for th mobile broadband sim card. if you have 3g capable phone it can serve as modem.i have been using it to my mobile sony ericson p1i.. im online to my messanger using software fring you dont need to sign out because it will only consume a very small kilobytes from your data allowance. its very mobile becuase you can go online anytime anywhere. you dont even need a laptop to surf or check emails you can do it in your mobile. the average bytes it will consume in on hour without downloading antyhing is only 10mb t0 15mb per hour. so 1gb is really enough. it is even smaller if you go online surfing using your mobile. hope it helps.