Question [Q] How to Unlock Samsung Galaxy S3 & S3 Neo

I have Samsung Galaxy S3 (Model No - GT-I9300 ) And Samsung Galaxy S3 Neo (Model No - GT-I9301I ) , I try to unlock the phone using *#197328640# code number, But no any responded in that devices.
Galaxy S3 Android Version is 4.3
Galaxy S3 Neo Version is 4.4.2

Please Help me for Unlock the country lock free of charge.

Any one know about this please quickly help me.