Re: "iPhone 17 Pro Max - FaceTime does not receive any calls"
Thank you for your post to he Community, and for sharing the good trouble-shooting steps already tried.
Keeping an iPhone updated (or upgraded) to the newest compatible iOS version often side-steps issues.
The newer versions often include bug-fixes, security updates, new features etc.
We can't guess which iOS version is installed on your iPhone 17 Pro Max:
For iOS 26 : What's new in the updates for macOS Tahoe - Apple Support says : iOS 26.1 is the latest version
or
If you prefer to stay with iOS 18 : About iOS 18 Updates - Apple Support says: iOS 18.7.2 is the latest version
You can check for updates in Settings > General > Software Updates.
Reminder: If you choose to update, or upgrade: It is always wise to back-up your iPhone first.
(It is not possible to go back to a previous version, the way of updating / upgrading is always forward.)
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Else: If you are already using iOS 18.7.2 or iOS 26.1 on your iPhone
If ou haven't already:
Restarting your iPhone is always a good first move, when something is not working as expected : (Deletes temporary files, re-establishes connections , may update recent setting-changes, and often restores order).
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Still need help ?
Apple Support's online article (link below) has trouble-shooting tips that may help:
If you can't make or receive a FaceTime call on your iPhone or iPad - Apple Support