What is the ruling on the fast of one who ate suhoor not knowing whether the dawn adhan had been called or not?

If you ate Suhoor without knowing the time of Fajr, then complete your fast, as it is valid, because the default is the continuation of the night. However, if it becomes clear that you ate after the rise of Fajr, then the fast is not sufficient according to the majority of scholars, and their opinion is closer to piety and caution.