Depends on the situation
Most of the time, I won't call the parents.
From experience, parents can only make things worse. I know they have responsibility for their child, but this is the child's life and their decision.
If it is a crazy/hopeless case, then I would call the parents and not hold anything back.
Anything else, I would negotiate with the student.
In the past, my dad frequently punished me for school/home failures (many were trivial), but it didn't improve me at all. In fact the more he punished me, the more I opposed him. He has his principles, and I have mine. Change comes from the will of the student, not from the parent.