I get numerous calls from a company trying to sell energy savings upgrades and solar. The call I received yesterday was from the same company but with a different number. Several times I have informed them that I am not in need of their services/products and have requested politely to have my phone number removed from their call list. That never happens. I suspect that either throw-away phone numbers are being used (such as a google voice number) or the a list of phone numbers is being sold or given to people to sell these services. Either way, they do not stop calling.
They called twice on my home phone one right after another and then immediately called my cell number. I do not answer when unknown numbers pop up. Just very annoying!