I had one SIM-card left that had been "grandfathered" into the current system, in which you are required by law to have the card registered with your social security number. Because Gestapo, that's why. Anyway, I was keeping it hidden away in my wireless earbuds' case, taped under the lid, but it must've gotten loose. Ah well... I wasn't really using it for anything, keeping it around just in case.