When I was in high school our home phone number was published in the phone book and military recruiters called it a few times when I was getting close to finishing high school.

I’m not giving my kid a cell phone if I think them having it would endanger them. If unsolicited phone calls endanger them they shouldn’t have a cell phone. They should know what information shouldn’t be given out to strangers over the phone, on a call or via message. They should know how to block numbers and recognize calls that are best left to voicemail, &c.