Why Should Kids Under 10 Years Old Have His/Her Mobile Phone?

To be on the safer side from negative impact of phones on children's physical interaction with real life, giving mobile phones to minor kids under 10 years old may not be accepted by many parents and guardians. However, for the safety benefit of mobile phones such as tracking the kids, when they are outside, kids who are 6 years old and above may have their parents' blessing of having their own mobile phones. Both opposing and supporting reasons should be fairly balanced, depending on the situations, parents' responsible characters, and parents' judgement. What do you think, dads, moms, and guardians?