There are three types of calls that get split out on the ICO’s complaint figures. They are SMS/text messages, recorded calls and live calls.
An SMS message is not that intrusive because you don’t have to really do anything. You can ignore it or delete it or, ideally, report it to the 7726 reporting service.
If a recorded marketing message comes through I can usually tell instantly that it’s not legitimate and just put the phone down.
Live calls, with a person on the end of the phone trying to engage in a conversation, can be a lot more difficult and upsetting when they are trying to mislead you. I tell people that there’s no need to feel bad about the person on the other end of the phone, as soon as you realise it’s not legitimate, for whatever reason. We Brits are too nice sometimes. You don’t have to be rude or shout or anything like that. You can just quietly hang up. If you say something like, “I’m going to hang up now” they’ll almost certainly counter with something and it gets harder to end the conversation, so don’t warn them. It’s not being rude, it’s just dealing with it in the best way. It certainly won’t be the first time they’ve been hung up on the other end of the phone.
Live calls are actually the smallest volume of nuisance calls that happen right now, because it’s obviously much cheaper to make recorded calls or to send people a text, but live calls tend to be the best way to engage people in a conversation and potentially lure them into a scam.