Won't do much for robocalls, but for people calls, you can always go by the "We don't use..." method.
"Hi, I'm Christine, calling from XX Hygiene Essentials..."
"I'm sorry to cut you off, but we don't use hygiene essentials."
"These are articles like soap and cleaning products."
"We don't use soap and cleaning products."
"You don't use cleaning products?"
"Nope. We like our dirt."
"I see... Well in that case, have a nice day."
"You too, Christine."
"Hi, Im Chris from XX Stream, may I speak to the person in charge of beverages and refreshements?"
"We don't use refreshments for our staff."
"Don't they get thirsty then? We are prepared to offer your company free beverages..."
"Our staff is not allowed to drink beverages. Only tap water."
"I see... We can deliver mineral water as well..."
"No thanks, the PH value is much too low in that garbage.""
"Oookay. Thanks for your time then... Have a nice day."
"You too, Chris."
"Hi, I'm calling from company X. Your company recently participated in one of our surveys, and we would like to send you a box of chocolate to thank you. Could I speak to the person in charge of Toner Cartridge aquisition?"
"I'm sorry, but we don't use toner cartridges."
"Don't you use printers."
"Sure, but we just throw them out when they're out of toner."
"Hello, I am Jonathan calling from X. We are offering companies in your area courses in personnel training and development. We would..."
"I'm sorry to interrupt, but we don't use personnel training and development. We prefer to keep our staff just like they were in 1980."
"Hello, I would like to speak to the person in charge of advertising."
"I'm sorry, but our company doesn't use advertising."
"You don't advertise? Then how do you get new customers?"
"We like our present customers, and don't want any new ones. We intend to grow old and die with our customers."
"Hello, this is Gia from Analysis Institute X. May I speak to someone over the age of 18 who drives a car?""
"I'm sorry, but we don't use cars."
"Then how do you get to work?"
"We are required to ride bikes by company policy. Our company is very environmentally conscious."
"Oh, how fascinating. Well not much point in me asking then. You have a nice day."
"You too, Gia."