can i unlock phone from different country?

My mum has sent me her Nockia 5800 Express Music phone from UK but it is locked to Virgin. I am in Australia. Can I use an unlock code from here? Just want to check before I buy one..
Thanks
I have been to virgin over here and other various phone shops but they just looked at me blankly. Unlocking of phones just doesnt happen here..

I suggest you can approach Unlocking4u.com and specify the country,locked network of Nokia 5800.Based on the availability you can get the permanent unlock service along with free instructions.