Upon enabling Call Screener, Hiya began screening all unknown (not in your contact list) callers for you. When you receive a call from an unknown caller (a caller not in your contact list), we block the call and send the caller a text message asking them to identify themselves.
To enable/disable this feature, tap on the gear icon on the bottom right for settings then tap on "Call Screener." You can then tap on the toggle to enable or disable the Call Screener.