Today I got a call from guy with a thick indian accent so I put the phone down but not he'd had time to claim that he worked for BT (I'm not their customer). How ironic to be getting that call just when BT announce their anti-spam call initiative (I wish them luck with that - but it's BT so they'll need luck).
I did wonder if the scammers might try using the anti-spam call initiative as a way to scam people "This is a call from BT. You'll have heard about our anti scam call initiative. To set you up on the new system I need [passwords, card details...]"