If you are not prompted to update your carrier settings, you can always search and install them manually:
- Make sure your iPhone is connected to a Wi-Fi or cellular network.
- Tap Settings > General > About. If an update is available, you'll see an option to update your carrier settings.
To see the version of carrier settings on your device, tap Settings > General > About and look next to Carrier.
Activation and usage of Sunrise extra SIM watch option requires carrier settings Sunrise 31.1 at least.