FaceTime is using data

Let's break down the scenario you described:

1. Connected to WiFi with no internet:
   1. When your device is connected to a WiFi network but doesn't have access to the internet, it might be due to various reasons such as a weak WiFi signal or issues with the internet service provider.
   2. In such cases, many devices have a feature called "WiFi Assist" or a similar name. This feature is designed to automatically switch to cellular data when the WiFi connection is not providing a reliable internet connection.
   3. The user can usually configure the settings for WiFi Assist. For example, they might set a threshold for the WiFi signal strength or speed below which the device should switch to cellular data.
2. Not connected to any WiFi:
   1. If your device is not connected to any WiFi network, and WiFi Assist is disabled or not available, the device will typically default to using cellular data for internet connectivity.
   2. In this scenario, the device relies on the mobile data network (3G, 4G, 5G, etc.) provided by the cellular carrier to access the internet.

In summary, the purpose of these features (like WiFi Assist) is to ensure a more seamless and uninterrupted internet experience for the user. They aim to optimize the use of available networks by automatically switching between WiFi and cellular data based on the quality and availability of the internet connection. This helps maintain a consistent and reliable internet connection, especially when moving between different WiFi networks or in situations where the WiFi signal is weak or unavailable. Users typically have control over these settings to tailor them to their preferences and data usage habits.