Hi is your Nokia 6300 mobile locked to network provider .Then visit Unlock-Zone.com here they render unlock code for all mobile models .Before paying for code check whether they are rendering code for your country and network provider to which your mobile is locked .If available  then pay for it and unlock your mobile.

Hi is your iphone 4 locked to network .Then visit Unlock-Zone.com here they unlock iphone from network lock using remote unlocking service .Before getting the service check whether the service is available for your country and network provider to which your iphone is locked at present .If available then pay for it and unlock your iphone4.After unlocking your iphone you can freely use any GSM sim in it.