Tethering and Mobile Hotspots

Tethering is a process where you share the internet connection of your mobile device to allow another handset to access the internet. The most common way of doing this is using your device as a Mobile Hotspot. This allows your device to create a secure Wi-Fi network for other nearby Wi-Fi enabled devices to connect to. 
How much does it cost to set up a mobile hotspot? 
If you have an applicable data bundle, data used by tethered handsets will come out of your bundle allowance. If you do not have an applicable bundle, data charges will apply for any data used by any connected handset, if your mobile handset is connected to the internet using the mobile network.  
Where is tethering available? 
Tethering is available in most countries, although there are still some operators and devices that do not support this feature.  

Some networks do not allow tethering on BlackBerry OS (BBOS), which includes the Blackberry 9720. 
How do I set up a mobile hotspot? 
Apple iOS 
Settings > Personal Hotspot > Change the Wi-Fi Password > Turn ON Personal Hotspot > Choose either Wi-Fi, Bluetooth or USB 

Visit the Apple Support page for more information
Settings > Mobile Hotspot and Tethering > Switch ON Mobile Hotspot > option More, configure the Hotspot details such as Password, Security Type and SSID name > Save 

Visti the Android Help page for more information
System Settings > Network and Connections > Mobile Hotspot select either Wi-Fi or Internet Tethering (USB or Bluetooth) > Configure Mobile Hotspot Settings > Save 

Windows Phones 
Start > All Apps > Settings > Internet Sharing > Click the Toggle Switch to enable Tethering > Click Setup and configure Broadcast Name and Password > Tap the Checkmark to Save 

For information, visit the Microsoft Support page