BT is warning customers to be on their guard after a series of phone scams involving people claiming to be calling from the company.
The scammers call up their victim and warn them that their account is in arrears.
They then ask for card or bank details in order to settle the account.
If the person refuses or asks for proof, the fraudsters then offer to prove who they are by disconnecting the phone line then and there.
Once the victim puts the phone down, the scammer stays connected to their line, thus giving the impression that the customer's line no longer works.
Andrew West nearly fell foul of the scammers' latest ploy in August.
But he quite quickly became suspicious of the caller's true identity.
He said: "It was the lack of background chatter initially; there was no call centre noise in the background, which there always is when someone from a big company calls you.
"The line wasn't very good quality anyway, which was a bit strange, but it was the trick with the phones that really tipped me off."
Evidence shows this type of phone scam has been happening all over the country.
Last weekend a number of elderly people in Suffolk fell victim to the scam; there have also been cases in the past year all over England and Wales.
Graham Preston, the lead officer for scams at the Trading Standards Institute, admits this type of phone fraud is around.
"Scams sadly are very common, they are variations of a theme and this particular scam seems to be prevalent at the moment," he said.
He warns people to be on guard.
"In terms of advising people, keep your wits about you, be cynical. If somebody calls you, mistrust them if you have to, or don't trust them," he said.
"Particularly if they are asking for money, if they want your credit card details don't be afraid to say no," he added.
Mr West ended up writing about his experience in his blog to warn other people about the trick.
He admits the experience upset him.
"I was a bit unsettled by it. I think it's one of those ones that if you didn't happen to know the trick, you could be easily taken in by it. It just makes you feel a bit nervous, " he added.
BT says it does sometimes make calls to customers about debt - but stresses that it never carries out disconnections during the call.
It advises customers not to give out any banking details over the phone unless they are absolutely certain who they are dealing with.