We'll soon be renewing our contract and getting new smartphones for both of us but we also have two lines on our family plan for my parents, who are just now getting used to the phones they currently have and don't want new phones. However, we could get them phones that would meet their needs at no cost with the new contract. Would it make sense to do that and not activate those phones, putting them away as backups in case something were to happen to one of their current phones? Is there anything that would require us to activate the new phones within some time period?