SkieWill Skie ever hide or break essential system apps like the dialer or settings?
No. Essential system apps are never touched by Skie, so the phone still calls, the clock works and Settings opens, whatever an app list says. Hiding applies to the other built-in and installed apps. This is the reason managed devices stay usable in an emergency.
A locked-down device is only useful if it still works. Android has a set of apps and services that the system needs, such as the system UI, the dialer, the settings and Play services. If those were hidden by mistake, the device could be left unable to call or even to start.
Skie never touches them. App lists decide about the apps a school or family can see, and the hiding or suspending applies to those. The essential set is excluded from that process regardless of what a list says, and the install guard does not remove it either.
The line between essential and optional differs by maker, which is the reason for the one-time model review during setup. The team maps the basics for each model, so that built-in extras can be hidden safely while the essentials stay. On a model that has not been reviewed, built-in apps are left alone.
That has an effect for calling. A device where calls are allowed can still make them, including to home. Outgoing calls and SMS can be disabled by choice, as optional switches, but that is a policy decision and not a side effect of app hiding.
Practical tip: if an admin hides something and a device behaves oddly, check the effective policy view for that group first, and the device's model. Report the case if a model hides something unexpected, so the review can be updated for everyone.