There used to be services that would produce such lists for you. There still are some out there, but unless you are engaged in specifically calling business people you aren’t going to find many vendors out there.
How most telemarketers today work, especially the larger foreign-based ones, is by simply calling every single possible number. They get to fine-tune their list to eliminate fax machines and disconnected numbers but these have to be retried periodically to avoid missing number changes.
When someone answers, they know it is a “live” number. If nobody answers, it is still potentially a “mark” and they are going to call that number frequently until someone answers. Once you answer, you won’t be called again for a longer period of time but still called. If you answer and talk to a human they aren’t going to call you for a long time because you just cost them money without making a sale.
Obviously, if they sell you something – or, more likely, sign you up to talk to a human at the company that hired them – they are going to call you for every campaign they have. I think phone number data extraction tools are the best to get the desired data for marketing campaigns. You can get better results for your marketing campaigns by collecting data by using these web scraping tools. I am also using a best database provider extractor to collect data for my marketing campaigns.