dude - your FICO score is your " I love debt" Score or "I care what banks think of me" score
If you truly live debt free you shouldn't care about your FICO score
Cell phone companies don't use the Traditional FICO they have an Industry specific credit calculation - but if I was debt free i'd probably look into something like Ting.
We have been working the Dave Ramsey Baby steps for the past month and we should be debt free except the house by the end of the year.
I have cancelled all my credit cards and I vow never to borrow money again - meaning I could give a flick about my FICO score..
Good luck to you
Ad astra per aspera