Recorded call on my iPhone, claimed to be a call from a prisoner at the San Francisco County Jail, but was free (not collect) and I could press "1" to accept the call. I hung up.
Got an automated call to my cell phone (listed as SF/North Bay Area) from this number saying it was from the Marin County Jail and to press a number to find out about my payment options or hang up to disconnect......hmmm. I don't know anyone in jail.