I don't know who (or what) the caller is, but they've been calling regularly - and getting blocked just as regularly - since May 31.  The calls have been as early as 7:48AM (which puts them outside the "technically legal" telemarketing window) and as late as 4:53PM.  On the first few, it was a dead line when picked up; since then, I've had the number blocked in PhoneTray, so I don't know (or care) what kind of call it may have been.