CHILDREN UNDER THE AGE OF 13

I think that children under the age of 13 shouldn't have a mobile phone, because the mobile phone is not esential for our life. In my opinion, if some children have got mobile phones there could be some advantages and disadvantages.
First when parents know where their sons are (in the park, at the cinema,...), they feel confident, although, children under the age of 13 shoulden't go out with friends until very late.
Another advantages, for example, can be if a child is stolen he can phone his parents more easily. I believe that a child don't need mobile phone.