Telecoms giant BT is to launch a "breakthrough" new service aimed at diverting millions of nuisance calls.
Most people receive an unwanted telephone call every month, mainly about PPI or personal injury claims, automated marketing messages or sales.
A BT team will monitor calls to the company's 10 million domestic customers and identify any patterns of callers.
The "rogue" numbers will be diverted to a junk voicebox, which BT estimates will affect up to 25 million unwanted calls a week.
BT customers will also be able to divert calls themselves to the "blacklist".
BT said the service, believed to be the first of its kind, will be launched later this year, harnessing huge computer power to analyse data.
John Petter, chief executive of BT Consumer, said: "Nuisance calls are one of the great annoyances of modern life.
"Everyone will have received one. We are delighted to have made this major breakthrough. We are giving control of the landline back to our customers and removing a major hassle and grief for millions of customers.
"We have been at the forefront of equipping our customers to defend themselves against the flow of PPI and unwanted marketing calls that has become a flood in recent years.
"Now we are able to announce that we are working to identify and tackle huge numbers of those calls in the network."
Mr Petter called on other telephone providers to join the fight against the "menace" ofnuisance calls, adding: "They can help us to root out the malicious players they may be hosting on their own networks when we identify dodgy and suspicious calling behaviour."
BT said it will share information with Ofcom and the Information Commissioner's Office.
Which? executive director Richard Lloyd said: "People are fed up with being bombarded with unwanted calls so this is a step in the right direction for millions of BT customers. We now need to see more action taken by the industry and Government to help reduce the stress and anxiety caused by nuisance calls."
An Ofcom spokesman said: "We've been working closely with communications providers to encourage them to implement innovative technical solutions to the problem of nuisancecalls.
"We therefore welcome BT's plans to intercept nuisance calls on its network and reduce the harm caused to consumers."