Where did this notification come from?

A

AC Question

So i have a samsung galaxy s4 and today for the first time ever this weird notification came up.. it wasnt from an app or anything, it was like a notification from the phone. It had the same format as the ones that tell you your battery is low and stuff like that, with the option to click 'ok'. The notification read: "Call me, i have no credit (and a random cell number here)" and the only option was to click 'ok' so i clicked it and it disappeared? Just wondering what that was and where it came from