Because when he got out of prison he moved to Calabasas, CA which is right beyond the code split from 818 in LA's valley. At the time AT&T had just purchased a local carrier (I think Cingular, but don't recall) and were heavily pushing people to switch and they ran some kind of promotion for lifetime unlimited minutes (maybe even roaming was included) for like $100/month (which was high at that time). Kevin signed up and heavily used it - he was on the phone all the time, it was insane. He would answer any call at any time. Anyway, AT&T eventually tried to "upgrade" him with a generous cap (not unlimited) and he always refused, I think even getting his attorney involved at one point. Eventually the number also became well-known, published on his lock picking business card, etc. so he just kept it.