iOS Update Blocker
Install an officially signed Beta profile to redirect your device to the Apple TV update channel, blocking iOS firmware pushes at the source.
Allow Profile Download
Install in Settings app
Reboot to clear Cache
How it works
This tool works by redirecting OTA verification nodes to the tvOS channel. As long as the profile is active, iOS will never find a firmware package for iPhone.
Rollback
To update, simply remove this profile in Settings and perform a full power-off restart. The official update channel will be restored immediately.