does anybody know how to get the ring tone that adults can't hear?

Question

the ring tone that one teenagers can hear it's also called The Mosquito noise

Answer 1

It would have to be extremely high-pitched (probably over 25,000 cycles per second). Are telephone speakers able to generate such a high pitch? Probably not, as that would drive up the cost of the phone a lot.

Answer 2

??? How does a phone determine if an adult is listening when it has to ring???