HI! i am from Serbia and i really loves Nokia phones.I buy Nokia Lumia 900 from person who told me,the phone network provider is Orange.This network in my country is not supported,in my country supported providers are,Telekom,Vip,Telenor.Can you please send me PUK unlock code for my Nokia phone.THANK YOU ANYWAY I LOVE NOKIA...
Only the network provider who SIM locked the phone can provide the unlock key. Please note, it is not a PUK code.
Also please note, Windows Phone 7 is obsolete for some years now.
Windows Phone 8 is currently reaching its end of life too.
There are unlock services on the Internet, but since I'm unable to sell my SIM free Nordic Lumia 720 and Lumia 630 WP 8.1 phones for the postage fee, I reckon you have been cheated if you paid any money for a SIM locked Lumia 900.
I suggest forget the Lumia and buy a current Android phone.
Neither Nokia nor HMD can help you with this unfortunately. In fact Nokia 900 is now supported by Microsoft, but they can't help you either. You need to visit a mobile phone technician shop in your local town, I'm sure they will be able to unlock your phone for a small fee.