The American state of Colorado is considering a ban on smartphones for children younger than 13. A Denver-based doctor - and father - is leading the effort. Tim Farnum is the founder of a group called ‘Parents Against Underage Smartphones.’ His proposal would ban sales of smartphones to children under the age of 13. It would also bar sales to anyone who wishes to buy such a device for anyone younger than 13. The measure would also require sellers of smartphones to provide proof to the state government that they have asked buyers if the phone is for anyone under 13. The proposal only concerns smartphones, and not cell phones without internet service.