The Communication Loophole
By default, if you receive a phone call on your iPhone and miss it, a notification remains on the lock screen. Incredibly, iOS allows anyone who picks up your completely locked phone to simply tap that missed call notification and instantly dial the person back. They do not need your Face ID, and they do not need your passcode. If your phone is stolen, a thief can use this feature to repeatedly harass your contacts or impersonate you. To lock down your cellular connection, you must sever this unauthenticated callback feature.
How to Turn Off Return Missed Calls
You can permanently hide outgoing cellular access behind the passcode wall via the Face ID settings.
- Open the Settings app on your iPhone.
- Scroll down and tap on Face ID & Passcode (or Touch ID & Passcode).
- Enter your device’s master PIN code to access the secure menu.
- Scroll down to the section labeled “Allow Access When Locked.”
- Locate the toggle switch labeled Return Missed Calls.
- Toggle this switch to the Off position (the green background will disappear).
Secured Telephony
The change takes effect instantly. The iPhone will completely sever the outgoing dialer API from the locked notification screen. The missed call alert will still visually appear on the screen, but if an unauthorized person taps it, the operating system will absolutely refuse to place the call. The interface will instantly prompt for Face ID or a passcode. This guarantees that your phone can never be used to initiate outbound communications without your explicit, biometric authorization.