If the phone unable to recognize any inserted working sim card to this solution below may help on fixing the problem.
Samsung Galaxy Nexus Insert Sim Problrm Solution
Samsung GT-I9250 Sim Pin Connecter Ways Jumper
Samsung I9250 Repair Sim Problem Track, Path, Solution
The solution below shows a detailed info about the Samsung I9250 sim card circuit. The image will help you determine of which particular parts or components needs to be cleaned, trace, check and or replace.