Tethering is included in your plan as part of your data allowance.
When you tether a laptop or tablet to your phone, the online data it uses comes out of your data allowance.
If you go over your plan's allowance, we'll charge you for data at the standard rate.
If you're using the 3G or 4G network, you can make calls on your mobile phone and use tethering at the same time.
If you're using the 2G network, your tethering session will be stopped when you make a phone call.
It's a good idea to turn tethering off on your phone when you've finished. This can help you avoid any unexpected data charges.
open your iPhone menu
go to General > Network
tap Internet Tethering to switch it off
open your phone's menu
go to Settings > Wireless & Networks
open Portable WiFi hotspot to switch tethering off
Settings may differ slightly on different Android devices.