Android
Set Up Fixed Dialing Numbers (FDN) auf Android
Fixed Dialing Numbers (FDN) is a SIM-based restriction, not a phone setting stored on the device itself. Once enabled, the phone can only place outgoing calls to numbers on an approved list plus emergency numbers. Incoming calls are never affected by FDN.
The feature exists mainly for shared, business, or child-use phones where outgoing calls need to be limited without removing the phone's ability to receive calls. Activating it requires PIN2, a second security code stored on the SIM card that is separate from the regular SIM PIN. Carriers issue PIN2 alongside the SIM, and it usually needs to be requested from customer support if it was never provided.
Where to find the setting
Go to Tap on Phone ➔ Open the Menu ➔ Tap on Settings ➔ Tap on Calling accounts. On dual-SIM devices, Choose a SIM card (Dual SIM) first. Then Tap on Fixed Dialing Numbers ➔ Tap on Enable FDN, enter your PIN2, and confirm with OK.
After activation, open Manage the FDN list to add every number the phone should still be allowed to dial. Entering the wrong PIN2 too many times can permanently lock the SIM, so double-check the code with your carrier before trying repeatedly.