Pleas for help to BT over malicious calls peaked at 60,000 per month last year but fell by a fifth after the introduction in November of "caller display" - the ability to see a caller's number before answering the phone.
In the past year, more than one million calls made to 65,000 customers were traced successfully at the request of the police, resulting in 2,800 prosecutions or cautions. In some cases people have been charged with grievous or actual bodily harm on psychological grounds.
BT said that "call return" - the ability to dial a code and hear the last calling number - has also helped cut the misery of victims. Further relief is hoped for following the recent introduction of custodial sentences for malicious calls and the increase from pounds 1,000 to pounds 5,000 of the maximum fine.
The latest report from BT shows that the worst repeat offender is a salesman in Rainham, Kent, who has paid fines of pounds 250, pounds 269, and pounds 750 in a series of cases, culminating in a conviction this year for making obscene calls to a 15-year-old girl. Because some of these calls were made from his work he was also charged with theft of electricity. He was jailed for three months for theft and fined pounds 1,600 for malicious calls.
BT has also helped catch one of its own engineers who threatened 140 women over two years to rape or kill them. He was jailed for five years after admitting threatening to kill and being a public nuisance.
BT said that calls to its specialist bureaux, set up three years ago, show that some people have suffered for more than a decade without knowing where to turn. There are an estimated 15 million malicious calls made every year, 10 million made to women, of which 60 per cent are silent.Reuse content