Unwanted Text Messages

I constantly get unwanted, often vulgar, text messages usually addresses to “Eric”, who I do not know. I have blocked nearly 100 numbers but continue to get them all hours of the day/night. What can I do? Is there a way to block all unknown text messages? Turning on the filter to block unknown text does not work. Is there a more advanced app? How can I stop them? Should I change my number?