I was amazed when I saw a 5yrs old boy calling his mom (Mom at work).
My 9 year old has a mobile phone.
It depends on d maturity of d child.
Not necessarily 8 more like when the child can do stuff like go to school or go out on their own so more like the teenage years.
@ damiso does that mean from age 8 to the teens age?
when he/she starts to leave the house without adult supervision i.e old enough to handle responsibility.