(Guardian (UK) Via Acquire Media NewsEdge) When Nikki Christie rang BT to ask why there were pounds 93 of mystery phone calls to Bosnia and Guinea Bissau on her bill - calls she knew no one in the household could possibly have made - the response, she says, was unequivocal: "There isn't a fault on your line. Someone in the home must have made them."
But Christie was amazed, and then increasingly annoyed, to find that many of her neighbours were in exactly the same position. Seven homes, it transpired, in Pelham Road, South Woodford, in north-east London, had seen in total more than pounds 1,000 of international calls added to their phone bills - some homes were charged as much as pounds 250. The calls were all made on the same date - 19 April - in the middle of the night, while the neighbourhood was asleep.
Despite this, BT staff insisted Christie and her neighbours were liable - despite the fact that the only possible conclusion was that someone had managed to hack into the phone system and charged the calls to their accounts.
The residents are furious because it has since emerged that while this is a well-known problem in telecoms circles, no one at BT had told the call centre workers - and as a result, residents say, they spent hours talking to customer services and getting nowhere. The fact that Sky customers in the same road, who were similarly affected, had the problem efficiently dealt with only added to their sense of frustration.
What the residents of Pelham Road did not know is that they had been victims of something known as "teeing", or "teeing-in". This sees fraudsters physically taking over a victim's phone line, by connecting a handset and using it to make calls - often to foreign premium-rate numbers.
According to a telecoms veteran, it can happen at the green boxes on street corners, or most likely, at the junction box next to the victim's home. While it's a fraud that can happen to any of us, few people are aware of it, and the telecoms industry appears to want to keep it quiet.
It was certainly a surprise to Christie, who says she has spent hours trying to resolve the problem. "BT's call centre staff have no idea what they are doing, and had I not been in a position to show that other people had suffered the same problem, I would still be waiting for a refund. I spent over an hour on the phone being bounced between the billing and faults teams.
"I spoke to at least six different operatives, and had to repeat my story to all of them. At varying points the Bosnian number was read back to me and I was asked if I recognised it. I was told several times that as there was no fault we must have made the calls, and it was suggested that we might have been out of the property and the calls were made in our absence."
She says that of the seven households she knows were affected, the five that are BT customers all reported having a terrible time getting it resolved.
It was a similar story for another victim, Vinoth Ramiah, who lives not far down the road from Christie in Ilford.
Ramiah separately contacted Money after he found pounds 225 of international calls to Bosnia on his most recent bill. The calls were all made on 6 April and occurred every 10 minutes, for the exact same duration of eight minutes, 55 seconds, and to the same three numbers. They started just after midnight and ended before 6am, but he says the BT call centre initially refused to acknowledge any fault and he was told that he was responsible for the calls - until, finally, he came across a BT staff member who recognised the scam.
Both Christie and Ramiah contacted Guardian Money after reading the story of a man from Leicester who found pounds 700 worth of calls to Iraq had been made on his newly installed line. At the time, BT told us that someone must have accessed the house, as it was not possible to hack a phone line.
A BT spokesman said: "The telephone lines of several Pelham Road residents were targeted by a criminal gang making fraudulent calls to international numbers. As a result of an investigation by the police and BT, three people were arrested and have been released on police bail pending further inquiries.
"We try to prevent customers being billed for fraudulent calls, but we may not be able to do this when the billing process is already underway. Where fraud is identified we try to prevent calls to the numbers concerned. We have credited the accounts of the customers affected. We apologise to customers who have had difficulties in resolving the issue with our advisers."
How 'teeing' works:
According to Andy Whale, a telecoms industry veteran of 27 years, teeing occurs when fraudsters illicitly connect cables or handsets on to someone's phone line - usually at a junction box either near the home or in the street. It can happen at the green boxes or cabinets that are found on many street corners and are relatively easy to get inside, or more often at the junction boxes near to where the cables enter the home.
"This isn't a new problem and is more common in blocks of flats where multiple lines enter a building in an accessible place. It's not that difficult to gain access to the junction boxes - usually a screwdriver can be used to open the boxes where it is possible to clip or connect on to someone else's line and start dialling.
"If the person in the home picked up the phone they would either hear the conversation, or if one of the wires had been disconnected, it would be dead, ie no dial tone. By the time they reported it, the thief may be long gone."
He says the thieves have been known to use these techniques to call premium-rate numbers abroad that can show up as standard international numbers here, but create a revenue in the called country.
"Teeing became increasingly popular in the nineties when premium-rate numbers first appeared, but the telecoms industry doesn't want to encourage copy-cat behaviour and so doesn't like to shout about it too much, so few people know about what can go on.
"My advice to anyone who is concerned, is to call their communications provider and ask for a specialist to investigate," he says.
Everybody needs good neighbours: Nikki Christie (with baby) and other residents of Pelham Road whose lines have been hacked Photograph: Martin Godwin
(c) 2014 Guardian Newspapers Limited.