I suspect these guys are computer hackers and that they are profiling/footprinting which is a fancy way of saying they are trying to find out as much about a target as possible so they can build a profile to help the hack a computer or steal an identity.
I say this because there is another thread going on where we're trying to track down what appears to be computer hackers who seem to be originating from Portland Oregon. On the same day people are reporting hack attempts many of them are also getting strange calls from this same number.