We have done this for years. Used to add money to our top-up card at Sharon's, but now will do it at the Mailbox. I just transfer $1 from the top-up card to the phone once a month when I close out my bills for the month. You do only have to do it every 60 days, but I don't want to take the chance of losing my phone number. By doing it every month, if I forget I have time to recover. Works like a charm. Still, very sorry to lose Sharon.