At least six households in one street appear to have fallen victim to a phone scam after receiving bills including calls to places a far afield as Guinea Bissau and Bosnia and Herzegovina.
People living in Pelham Road, South Woodford, were charged about £250 each, with the bills showing the mystery calls were all made on the morning of April 19.
It appears they have fallen victim to a phone scam, but have yet to be told how security was breached.
Nathan Leaman-Hill, 44, received a £256 bill from Sky and has warned others to check their bills.
He said: “We all received a scare that morning. I found Sky had automatically shut down my landline to foreign calls and alerted me by text.
"I quickly got in touch with others in the street and they said they were having the same problem. It is a real surprise really as landlines are meant to be secure.
“We want to speak out and make sure everyone in the area checks their phone bills because they could be in for a nasty shock.
“You just imagine an old lady not fighting this bill, whereas we were all on the phone straight away to get this sorted.
If we were not so vigilant about it then we could have lost the money.
“We do not know what has happened.
Brian Phipps, 67, received a bill of around £200 from British Telecom, and is worried it could happen again.
He said: “We have received no guarantee that we will not see a repeat of this so it is worrying.
"I was not alerted to it happening, I was lucky we have a network here and Nathan contacted me.
“I checked my bills and couldn’t believe it, I just wondered what was going on really.
"I was pretty sure I wouldn’t have to pay the money as it was clearly not me.
“I was told by the call centre in India that I didn’t have an account, and then I was told it was impossible that this could happen.
“We want to know how and why this happened.”
The Guardian is awaiting a comment from Redbridge police.