Got a call around 9:45 am today Sept. 1.  I didn't answer. They called back immediately.  When I answered no one spoke.  I said hello several times and a foreign high pitched voice would repeat hello after I did but I also heard was seemed like an echo of my voice but it sound as though my voice was put through a voice changer making it a lower pitch.  I've recently heard about hackers/stalkers being able to get into your cell phone and have access to to power up your phone, speak to you, hear your conversations through the speaker phone and possibly be able to see through the camera on a phone. I believe it was on a morning program on CBS within the last couple of days.  It is being called stalking by the police and FBI.