We run out of available Call Block slots on a nearly bi-monthly basis. We just clear out the oldest 10 or so to make room. Once they've been blocked for a few weeks they don't really try back. Not sure if your call-blocking phone is the same, but when they try to call it's pretty clear to them they've been blocked. Hope that helps!
Just noticed their call. We have the entire 720 area code blocked. Our phones do not ring when a blocked call comes in and our office is not disturbed. We have the Digitone blocker that blocks not only individual numbers, it can block entire area codes. We have all area codes from Washington state blocked. Currently we have 44 area codes blocked and another 50-60 phone numbers blocked. Sadly, our Digitone Call Blocker is full!
Save your sanity - buy a call blocking phone or device.
BTW, I understand that Digitone will be coming out with a newer model in March. The new Digitone (when available) will operate in conjunction with the old one and will allow even more numbers and (more importantly) more area codes to be blocked. We are a local business and rarely (if ever) do business with the east coast and Washington state. The blocking of area codes seems to be the most beneficial for our business.