Oldest son got his first phone 8 years old. His brother got his two years later at same age.
I was angry at my husband, when he upgraded the phone for older son at age 11-12. He bought a phone worth 200 euros! Even angrier, when it shortly ended up in washing machine with his jeans. It didn't recover...
Another mishap was when younger son was able to spend a huge amount of money on text messages during one day when participating in a competition.
We (my husband) is a bit wiser now and they have some limitations to prevent more costs.
I have not allowed my husband to buy himself a new phone, he usually gets an old one from his work-mates, I don't need a fancy mobile either. We have one or two old phones left from boys and recently hubby ordered a SIM card for my daughter on one of the old phones. Daughter is 5 and daddy had promised her a SIM card, when she learns to read...
she reads now, has only a couple of numbers saved on it, she can talk worth 10 euros per month. First week had gone and she had already used 50% of that amount. Oh well, maybe this will teach her about the passage of time as well...