What age did you give your kids their own mobile phone?

i don't know why parents are so interested in giving their kids a cell phone, saying it is for their safety. in most cases, our children go to school in the school bus and come back home. they can always use the home phone to call parents in case of an emergency if parents are not around, and do the same from the school phone too. giving phones to kids is only increasing the danger of them getting exposed to social media and other online dangers at a young age.