Navifirm Plus - what exactly is it? Well, for better understanding I’ll explain a bit to you.

Navifirm Plus
It is a software used to download Nokia phone firmwares from the oldest to the newest. This is very useful if you’re someone who loves trying out latest firmwares in advance or if you want to use a CFW (they are essential for restoration and some files are also used with CFW or custom firmwares)
However, using it comes along that responsibility of knowing what your firmware is because even if you find your Nokia phone model, there are different ones from different countries and different versions.
Now, flashing the firmware to your Nokia phone is another thing which is done with JAF or Phoenix. Remeber though never ever flash older firmwares than your phone’s because it will brick it.
To find out your phone’s correct firmware, simply find out through dialing *#0000# while active. Then turn it off to take out the battery, at the back, you will see a code

Code and Firmware (version can be found doing *#0000#)
These tools are a must if you wish to explore your Symbian phone in so many ways. Just be very careful in the files you will download and double check firmware versions.