unable to connect internet in Iphone 5S. Showing not subscribed

Hello,

I recently bought Iphone 5S. I have internet package for my cellular network connection. When I am using my SIM in Iphone showing network Sysmbol "E" but unable to connect to internet showing below error.

Error: Could not activate cellular data network. You are not subscribed to a cellular data service.

Could you please support in accessing internet. Wifi is working good. but problem with cellular data network.

Thnaks and Regards,

Sunil