got a missed call at 2:19pm and when tried to call back it would'nt ring

If you answer, automated machine says they're from Global Market and that you have a collect call from an inmate at some jail, but that I must set up a prepaid plan. If you don't pick up, they leave a message with the same info. although the messages they leave vary slightly from one another. If you try calling call, there is no ring tone (no ring).

i got the same message that george had i would like to know what is this about because i got already 2 calls.