I received a warning notice from the court for no reason.

No state organ, let alone the people's court, will use voice service to do things. According to the provisions of the Civil Procedure Law, even if there is a lawsuit, the court will first serve you with a copy of the complaint and a notice of responding to the lawsuit. Even if it is a summons, it is in written form. You should not ask for personal information such as your ID number on the phone. To sum up, you are very likely to meet the legendary liar!