Why my sim can't work in iPhone 4 can gevey sim work in it

If it doesn't work, it may be locked if it originally came from a carrier. If it's not locked it should work with different sims. If locked, it's locked to the one carrier until released. You'll need to find out where this phone came from and what company if purchased from someone else.

Some Iphone updates will also update carrier settings, for that unit I believe it's 10.3 that is the most recent update.

The other thing to inspect is for damage in the sim reader and or possible water damage.

Other test:

Put the sim in, manually restart the phone, check if connected. If not, go to carrier and manually search for the network to see if it's able to discover it. I'm not entirely sure if it's the carrier update or what but whenever I put a sim in this unit I have to manually restart the phone in order to discover a network.

Good luck