Note:The N73-5 RM-132 is a Non-3G variant of the N73 while the N73-1 RM-133 is a 3G variant and supports 3G in WCDMA 2100 Band.
To convert your N73-5 to N73-1 to support 3G you will need a CA-53 USB Data Cable,Nokia Phoenix Service Software 2007(2006 might also work) and a RM-133 Firmware.
Follow the steps mentioned below:
1]Plug the USB connector of the CA-53 Data Cable to your computers USB port but don’t connect your phone yet.
2]Install the RM-133 Firmware
3]Open Phoenix Service Software 2007 and click maintain and add new user.
4]After adding details select the user and click OK.The Phoenix main window will open.
5]Now choose file menu and click on Open Product.
6]Select RM-133 from the list and click on OK.It will take some time to load since the phone is not connected.
7]Choose the flashing menu and click on Firmware Update.
8]The Firmware Update window will appear but since the phone is not connected it will take some time to load.
9]In the product code section select your product code.For eg APAC 1 or APAC 2,EURO 1 or EURO 2.
10]Now connect your phone to the PC by the CA-53 Data Cable and select PC Suite mode.
11]Click on OK in the Firmware Update window of Phoenix.Now after it verifies connectivity with the phone it will restart the phone and start flashing.Don’t touch the phone while the flashing process otherwise you have the risk of a dead phone.
After this you can also change your N73 to N73 ME by just changing the product code via NSS or manually downloading the firmware and flashing it.
Backup all your important data such as contacts and messages before flashing.
You can void your warranty by converting your phone but it is not yet confirmed.
If you are a noob at flashing phones then please consult me before flashing.
If you don’t have a CA-53 cable then you will need to purchase it.It is available at any Nokia shop btw it also comes with every N73.