Which part of the response from others are you missing? As mentioned more then once NO, NADA, NOT POSSIBLE the BB 5810 will not communicate on a GSM900/1800 netwwork (I repeat it will not work) it wasn't designed for it. If those are your requirements your going to need to purchase a newer model.
Originally Posted by NJBlackBerry
As both Finch and I have said, the 5810 only runs on the 1900 MHz network. THAT'S IT. There is nothing you can do. No mainboard, no SIM, no magic. If you need 900/1800, you need to get another BlackBerry. Just not the 5810.
Originally Posted by nothao
pls advice how to use this BB5810 for GSM900/1800GHz
tks a lot