[brianaker]

Managed Networks are loaded via the carrier profile. The "attwifi" SSID is defined in:

Payload/ATT_US.bundle/profile.mobileconfig

You can find the the carrier file, i.e. the ipcc for AT&T here:

https://updates.cdn-apple.com/2022/carrierbundles/002-77749/...

Just unzip the file in order to see its contents.

If you remove the SIM card from your iPhone the managed networks are removed. If you have disabled any of the Managed Networks and remove/reinsert your SIM card the networks will be re-enabled.

Once upon a time you could edit and load your own ipcc carrier bundle, I do not know if this is still the case. ( Whether this has ever been ok/allowed/etc,... I have no idea. )