SIM Tool Kit, or Service Text Messages (the functionality is the same). It is sometimes also called the SIM Application Toolkit. These are binary SMS messages sent to the phone, mainly by Operators but also by our customers, to update the SIM card and/or the phone with service-related information. Examples where STKs are used:
- Enable the phone for Internet connectivity
- Update prepaid phones
- Activate new phones/SIM cards
- Upgrade phone ROM/Flash memory software.
