The SIM Toolkit is a standard set of protocols and applications that reside on your SIM card, not on your phone’s internal memory. It allows the SIM card to interact with the phone to perform specific actions. Think of it as a mini-operating system embedded in the chip of your Airtel SIM.

The icon may not be on your home screen. Swipe up/down to reveal all apps. Look for a folder named or “Tools” where your carrier apps might be hidden.