Like most people today, I tend to screen all my landline calls by caller ID, but that's not always useful due to masking and spoofing.
For the most part, I am polite but insistent in stopping their sales pitch at the moment I am certain I don't want or need what they are selling.
For charities, at least those I can identify as valid, I will listen longer.
For scammers, I am not at all hesitant to scam them back: "Good morning, FBI Northeast field office, Agent Mulder speaking, how can I help you?"