Call Customer Care at  833-50-BOOST (833-502-6678) as soon as you realize your phone is lost or stolen. We can take measures to protect your active account balance as soon as you call in, and get you up and running again. Once you report to Boost Customer Care that your phone is lost or stolen, you will have 60 days to replace your phone; otherwise, your account will automatically cancel and you will lose any money you had left in your account.