Most usually hang up straight away when you tell them you are registered with the TPS.
Infact, most of the calls I get through now (after getting about 10 everyday when I first had the phone line put in) are from what sounds like foreign call centers, where they can probably get round it as they aren't UK based.
I had one Indian sounding guy who phoned up a few days ago and said "Hello, I'm from the Internet Protection & Security department". (LOL WUT!?)
"Of which company?"
"The internet protection and security department sir"
"You said a department... what company are you? Why are you calling me?
*Caller hangs up*
I tend to mostly get cold calls from fax machines though, even though I registered with the fax opt out service too.
I think they can occasionally be quite good fun though.
A recent one was from some company that had somehow got my data and knew my name and had rung up to offer me a gift voucher to spend on home improvements, such as conservatory, extension or loft conversion. She was reeling it off without letting me get a word in saying it wasn't a sales call and just wanted to know what the one thing I would like to improve in my home was, whether it was a conservatory, an extension, loft conversion etc.
I told her that I'd love a conservatory (I live in a Flat!).
She started yapping on about them... at which point I asked her how you would go about putting a conservatory on a flat and whether it was more expensive than a normal one! She was like... "Oh, sorry sir, the details I have for you must be wrong, I had you down as a house."
"So you can't put a conservatory on my flat?"
"No, terribly sorry *starts making excuses*.
"This is a sales call isn't it?"
"No *excuses*.
"I'm registered with the TPS, remove me from your database and don't ever call again."
*Caller hangs up*
A friend of mine actually once strung a guy in a call center along for nearly an hour talking about his life, by trying to change the topic everytime he tried to sell something. He put it on speakerphone for us to listen and put on a ridiculous dutch accent... was hilarious!