@Sheeba13. Product codes.
The latest software (firmware?) for the phones is the latest that Nokia supplies for the phones, but if your phone is on a contract with a network it is for that network to approve the software released by Nokia. They will also fiddle with it to add their logos and so on to the software. So, if you buy an unbranded phone from Nokia, you will be able to update it as soon as Nokia release the new software. If you got the phone through a phone network, I'm afraid you will just have to wait till that company approves it.
The product code relates to different models of the same phone, so although yours might look the same as an unbranded phone, the product code identifies it as belonging to a certain network or region. The only thing you can sensibly do is to wait till your phone company approves later versions of the software. You could contact them and ask if they will allow you toupgrad e to a later version, but I think I know what their answer will be, and it isn't 'Yes'! But, worth asking, perhaps... 
