It may not necessarily be from any jail, but a company in charge of dealing with calls from inmates. They're a real stinker to get mixed up with if you have an acquaintance in a facility. If you know no one locked up, odds are favorable it's to trick you out of money and financial information. Random calls from "inmates" seem to be a popular trick these days, but if you do have somebody in jail, they can pilfer you out of money in a flash. Securus and Tele City Coin are two providers and they're repulsive thieves.