That's my approach as well, but I had the same number calling me for 3 weeks and I finally answered. It was my electric company, something had gone wrong with a payment.

They have my email address, they send me txts all the time, but apparently collections is still making phone calls. Had to be the dumbest thing I'd seen. Once I answered and found out the issue, I paid the bill properly, but I wonder how far it would have gone before they cut off my power, while they kept sending me emails and txts about things that have nothing to do with my bill.