I've gotten a call from these people the past couple of days. When trying to call back the phone didn't even ring. Very creepy.
For those who have the new update on the iPhone, if you go to your Phone app and touch Recent on the bottom of the screen the number will appear there. Next to the number should be an i in a circle. Clicking the i will bring you to an information screen giving you the option to Call, FaceTime, etc. If you scroll all the way to the bottom there is an option called Block This Caller.
I get this calls often throughout the day and weeks there are times I get several in a day, I try to call back and there is nothing going on the phone, just a dead sound. Very strange they call then the calls stop. Then a few weeks later start back up again and always on my cell. This is the number the calls are coming from 415-363-9713 I have no idea what/or who it is. No company called me they are on my recent call list.