@silkevicious Or they're lazy and don't clean their lists.
My favourite is when we get calls trying to sell us VOIP or Internet services:
𝗠𝗲: "I take it you didn't look at our website before calling us? We're an independent ISP and provide our own Hosted VOIP services in conjunction with BT Wholesale. I could more than likely sell that service to you far cheaper."
𝗖𝗮𝗹𝗹𝗲𝗿: "Oh? Umm? Err? Ooh."