What does SIM Toolkit app do?

Dual SIM iPhone: How To Access SIM Applications (SIM Toolkit)

SIM Toolkit App Not Showing? Do This Now (Fix in Minutes!)

What is SIM toolkit and how does it work?

SIM Toolkit, which is already installed in a phone when you buy the mobile

Why is SIM Toolkit on my phone?

What is Virtual Topup Sim Card Application In Android || Sim toolkit Service

Hacked Sim toolkit and Workspace apps