[Q] How to make the Sprint HTC Desire 510 useable on GSM networks? (with sim card)

Hello, I have the Sprint HTC Desire 510 version. Im from Israel, And I've managed to get S-OFF and unlock the device with the Sunshine APK.
I Insert a local GSM sim, the device dosent seem to read it. Plus, I didnt activate the Sprint activate method. Will flashing a new rom will help to use the GSM sim? or theres some other method I should do inorder to make it work..?

Thanks a lot for helpers.