The average British child receives his or her first mobile phone at the age of 11, but nearly one in ten has a phone by the time they are five, according to a new study.
Children spend an average of ??11 a month on mobile costs, less than the parental average of ??19, though just a quarter of parents cap their offspring's mobile phone bill, research from uSwitch.com showed.
More than a million current under-16s had their first phone aged five, the study of 1,420 parents suggested.
When shopping for handsets, parents spend an average of ??246 on themselves, more than the ??125 they typically spend on the children's devices, uSwitch said. However, 15 percent of youngsters under 16 have mobiles worth more than their parents'.
"As well as arming kids with mobiles for emergencies and peace of mind, I'd imagine that many parents have bought their kids smartphones just to stop them commandeering their own when bored," said uSwutch telecoms expert Ernest Doku.
"Smartphones are getting more affordable all the time, with entry-level models costing as little as ??7 per month with a free phone or ??29.99 for a SIM-free handset."
He cautioned, however, that more parents should set limits on their children's phone bills.
"Asking networks to place caps on their mobile bills takes about five minutes and is a very sensible precaution, especially if your child has a data-hungry smartphone," Doku said.
"Make sure that when they're at home, your kids are browsing the web using Wi-Fi instead of consuming data by connecting to the internet via 3G or 4G."
Only 3 percent of parents disable the data function on their children's phones so they are only able to use them to call and text, the survey said.