Once you have documented your ECID and registered it with a blob-saving service, you gain long-term flexibility over your device configuration.
If the Serial Number field doesn‘t cycle through to ECID: ecid register iphone exclusive
It cannot be changed, spoofed, or deleted by software updates, factory resets, or jailbreaking. Once you have documented your ECID and registered
Within jailbreak communities, a different form of “registration” exists through ECID caching. Servers like Saurik‘s Cydia server cache SHSH blobs — signatures that contain your device‘s ECID — so you can downgrade firmware later even after Apple stops signing that version . To use this feature, advanced users modify their hosts file to redirect iTunes to a caching server that stores ECID-bound signatures. or deleted by software updates