I am repeatedly being called by what shows on my Dect phone as an 0800 number. I suspect that this is a scam, maybe to get you to call that number then being relayed onto a premium rate number. Anyone got any ideas on this?

It doesn't matter where they transfer the number. The number that you called, presumably on your landline, was the 0800 number so you will be charged the 0800 rate, ie. NOWT !!   :-/

0800 is a FREEFONE number.

It doesn't matter whether the voice on the other end says about "this call will be charged at £500 /minute" or nothing at all.

IT's FREE !!!

So it appears that this is an advertising ploy to get you to call a number to advertise their product. It gets very annoying, it can happen at anytime, day or evening. It is evidently an auto-dialler as it drops the line when you pick the phone up.

I've received calls from BT (more than once) on an 0800 number - usually someone speaking an unintelligible version of english and trying to sell me some feature I don't want.

BT have been phoning me with CLI showing an 0800 number. It's basically a sales pitch trying to make you return to BT. Actually their Option3 replacement at £4.75 for all UK geo calls isn't a bad deal but I don't want oiks from BT smarming me. At least this one was a native English speaker and was trying to be charming. When I reminded him I was on TPS he said he wasn't seliing anything.

Also been getting a few calls with a faked CLI starting 0866. The one that I answered and wasn't silent was obviously a "Boiler Room" financial scam.