I suspect (because I never answer) this is the same caller that has been plaguing my cell phone for weeks and they just keep changing their number. It is the same call pattern every time. They call 3 times in less than 5 minutes then repeat 3 or 4 times in the week. I have blocked the numbers, but that's why I suspect they are just changing their number
this number called my cell phone so I called back on my land line and a recordings said "the survey is now closed, if you would like to be removed from the call list press 9".