Criminals are exploiting the lengthy call clearing times to trap gullible victims.
UK phone companies are modifying their networks amid increasing fraud in a bid to drop features that are exploited by cyber criminals.
Hackers are exploiting ‘call clearing’ systems that facilitate transferring calls to extensions in homes by keeping a line open even after the customer being called has disconnected.
Criminals are making use of the lengthy call clearing times to make it appear as if the caller is speaking to a bank or police.
The British phone operators including BT, Sky and Virgin Media have revealed plans to slash call clearing times from minutes to seconds to prevent criminals from exploiting the loophole.
According to a BT spokesman, call clearing times would stretch to two or three minutes on some of the British networks while its requirement had been minimising.
"We intend to cut the ‘holding the line open’ time to two seconds and we will have a solution in place to do this for several million customers over the next six weeks," BT told the BBC.
"We need to do some further testing for the remaining lines and will resolve this issue for those customers as soon as possible."
Virgin has also been developing ways to bring down clearing times on its network.
The feature is often exploited by fraudsters by calling their victims in guise of a call from the bank, ISP or police asking for credit card details.
Virgin Media spokeswoman Emma Hutchinson said: "If someone is concerned about a call they’ve received, they should hang up and either wait five minutes or use another line to speak to the police on 101."