First, you have no way of knowing with any certainty that the teacher did not speak to the other students' parents. Even if they told you the teacher didn't call, it is not at all unusual for students to lie to their peers to save face. Secondly, you did swear in class, and it is pretty normal for there to be consequences for that. It was a phone call as a consequence of your behavior. That isn't a huge "punishment"; you weren't referred to the office or suspended or anything like that. Sounds like your parents handled it well on your end. Why are you hanging onto this 12 years later might be a better question?