Don’t get many, we used to see how long we could keep them on the phone for with the wildest tales. 48 minutes was the record from a lad who had his head cut off in a road accident.
Had the same about boiler cover. Politely said I had cover amd could they take me off their list and just carried on with the spiel!
I haven’t connected mine in the last 3 houses I've lived in. I know I've got a land-line number because Internet was cheaper with a land line than without but I've no idea what that number is and I haven't had a phone connected to a land line in a decade. I don't even own one that could connect. You don't get spam calls on mobiles as you just block the number. I've also blocked all companies that I do actually have an account with. They don't have anything to say that I want to hear that they can't put in an email.
Ask them if you can call back later… when they give you a 0898 number or whatever, inform them that you need their own personal number and that you’ll ring them at 11pm that night. They reply with something like “I’ll be at home then and don’t take calls”…. then wait for the penny to drop.
If I don't recognise a caller. Be it on mobile or landline. I don't answer. If it's important they'll leave a voicemail. Very rarely, if ever, happens.
Caller display shows their number, or withheld, or international, or summat similar. I just ignore them. Or if I'm feeling cheeky I pick up, tell them I'll fetch the person they want so please wait, then play them some jazz down the phone. Five minutes later you hear the long tone meaning they've hung up.