I keep getting these scammers. They start off by trying to sound "official" and citing some usually fictitious, but credible, authority. If you want to play along a little, start quizzing them about the exact designation of the authority on whose behalf they are supposed to be calling. The script from which they're reading very quickly falls apart.

Mostly, I don't answer if I don't recognise the number. If uncertain, I look in local.ch. I omit the last 2 or 3 digits (just in case it is from an individual number within, say, a business I do deal with) and call back ONLY if it is someone I know that I want to be speaking to.

Never, ever call ad advertising number back, as some of them direct you to chargeable numbers, where you will then be billed for the minutes it takes for you to speak to them to figure out what they wanted from you.

If I decide it's spam, I block the number, and that's that.

If ever I do answer, as soon as I detect that the call is an ad, a survey, or suggestion to provide me with a new product or service, etc., I say: "No advertising on this number," in the language they called in, and hang up. And block their number immediately.

If the caller is legitimate, and it turns out that I've blocked them when I ought not to have, that's no matter, as they will find another way to reach me, be it by mail or post.

I find that advertising calls come in waves, from many different numbers, but after a week or two of "no", consistently, the calls dry up.

Not necessarily. They may have a dialing robot that randomly generated your number.

Far too complicated. I never call back missed calls, unless it's someone I know who could be calling just for a chat. Anyone else who I'm dealing with in any capacity should have the nous to leave a message if they want me to call back.

It's not as if anyone (surely?) doesn't have voice-mail/answerphone these days, so if they don't leave a message they don't get called back. Simples.

I find it amusing that some people consider it worthwhile to make an effort to waste the cold-callers time, yet at the same time I know people who are reluctant to be rude, so will wait for the caller to ,make their complete opening pitch before politely saying they're not interested. Just hang up, no need to say anything/

I typically troll them by feigning interest and then slowly softening them up by saying increasingly unlikely things.

But if i can't be arsed or don't have time for that, I don't hang up but leave the phone off the hook so they can keep talking to themselves and waste as much time as possible, just occasionally picking up the phone and saying things like, sorry, can you say that again.

the record so far is that I kept somebody talking for almost 20 minutes.

Well, much as I don't like such calls, only some of them are scammers.

Others are people working for low pay in miserable conditions in a call-centre. Some get paid on commission only, or largely on commission. And yes, this can be so, even in Switzerland.

Once I understood that, I realised that it is unfair on those individuals (who've taken on a lousy job as better than none, to try to pay their way in life) to let the call go on for any longer than the absolute minimum, so that they can move along from disinterested me to someone who might actually want to buy whatever they're selling.

Unfortunately that enables them to find unsuspecting victims like this one ...

Broker lied and made me sign official documents

Yes, some brokers do lie. And some people foolishly sign documents they have not read nor understood.

But not all call centres are scams. I know people who have sold, and who have bought, as a result of the call from a call centre, and both are satisfied with the transaction.

Just as I don't want call centre callers to waste my time, so I don't want to waste theirs.

If they did not know my name, I would make an appointment at an address I don't live at, probably say I was Herr Chuff or Edwin .

Typically I only do that if they refuse to accept when I tell them that I'm not interested, and just rattle of their script nevertheless.

With me, they never get that chance, to accept or to refuse to accept, as I've long hung up and moved on to do something else with my time.

There are many other jobs they could do... they make a conscious choice to harass people.

I've known several people who've had the displeasure of working at out-going call-centres. Each one of them would have gladly jumped at the chance to do just about any other kind of work. They hated the fact that their phonecalls came across as harassment, and they even thought so themselves.

They were there, making one boring phonecall after the next, because they lacked the skills or qualifications or working experience to do many other kinds of jobs, and because they were determined to try to earn, rather than to have to claim social security benefits.

Your sob stories are both predictable (you seem to have one for every occasion) and irrelevant and I have zero sympathy for anyone who makes a conscious choice to harass other people. They could do many other kinds of low-skilled jobs.

For a long time I had some sympathy with the callers, but you do need to understand that what they're doing is illegal. Cold-calling people who have a "no advertising" mark in the phonebook is simply illegal and I've lost sympathy with someone who's carrying out such activity.
Some time ago, one guy tried to come back at me by saying he "was simply following orders". I retorted that the last people who used that excuse found themselves dangling at the end of a rope and that he had to take responsibility for his actions. Probably didn't help.