how to change your phone's firmware:

Before upgrading your phone, as mentioned here, you can also change other things too. Like make it have another language... for make it silent, meaning to take out that camera shutter sound. If this is the case - you will need to download and install NSS.

Download it from here .... then install it.
http://www.b-phreaks.co.uk/NSSDownloadLanding.htm

Just follow the ff steps. (steps taken from upgrading an N73)

1) After installing NSS.... connect your phone to your PC. Choose "PC Suite" mode on your phone. (so that your PC can "see" or detect your phone).
2) Start NSS.
3) Push the button "Scan for new device"
4) Go to Phone Info screen. Check and enable the product code box in the right corner. Change the number there to N73 ME product code number 0539343 for APAC 1 -> Chinese, English and copy that number into that product code box and then click that enable box. (note your original N73 product code up, in case if you need it again). Then click WRITE, and in few seconds click READ, and you'll see that your phones product code has changed.
5) Then exit NSS, disconnect your phone, then connect it again ... start NSU this time, and follow the steps. (to upgrade your phone).

You will now have an upgraded phone with a different regional product code.

cheers!