iphone 4s sim not valid ios 7.1.2

Hi k.j.bamaniya,

If you are getting an error message saying that your sim card is invalid, I would suggest that you troubleshoot using the steps in this article -

iPhone: Troubleshooting No SIM

http://support.apple.com/kb/TS4148

Specifcally -

1. Update your iPhone to the latest version of iOS.
2. Toggle Airplane mode On and Off.
3. Try turning iPhone off and then on again.
4. Check for a carrier settings update. Tap Settings > General > About. If an update is available, a prompt will appear.
5. Remove the SIM Card and verify that it is a valid, carrier-manufactured SIM. Also verify that it is not damaged, worn, or modified. Then reinsert it.
6. Restore the iPhone.

If you still are unable to resolve this issue, contact Apple support for further assistance.

Thanks for using Apple Support Communities.

Best,

Brett L