Around 100 people are being plagued by malicious phone calls every day despite the efforts of a special unit set up to deal with the problem.
The Malicious Calls Bureau is dealing with around 26,000 complaints a year, just slightly less than the 30,000 it dealt with when it set up in 1998.
Those behind the calls included former partners, bored schoolchildren and people with personal grudges.
Around 48 per cent of the calls dealt with last year were threatening or abusive, 35 per cent were silent calls, eight per cent were hoax calls and nine per cent were electronic, involving faxes and power dialling.
Eircom, which operates the Malicious Calls Bureau, said that around two-thirds of the cases were resolved after the victims received advice.
"The remaining one third would have changed their number or requested the gardai to trace the nuisance calls," said spokeswoman Grainne O'Malley. She added that the level of malicious calls had remained more or less constant over the last number of years.
Women made 57 per cent of the complaints, with men accounting for 41 per cent and businesses 8 per cent.
The number of malicious calls increases after pub closing times and after school hours.
"People who engage in hoax or nuisance calls possibly don't realise just how seriously they are dealt with. There are fairly hefty fines or a prison sentence," said Ms O'Malley.
Under the Wireless and Telegraph Act, malicious callers face fines ranging from €1,000 to €63,500 or a prison sentence of up to five years.
Last month, a Leitrim farmer was jailed for a year and fined nearly €2,000 at Sligo Circuit Court for continually harassing a girlfriend he had broken up with in 1989. John Mulvey kept up his phone calls and text messages to the woman even after she married and changed her number, culminating in a night in July 2003 when he called her 29 times.
Other cases which came before courts include a 25-year-old Tallaght woman who made 363 silent phone calls the mother of a woman she was in dispute with last year.
A Dublin publican made dozens of nuisance phone calls to staff in state bodies in 2003, while a Cork secondary school student harassed his business teacher with up to eight telephone calls a day in 2001.
In one of the most disturbing incidents, the families of two young boys killed in the Omagh bombing received malicious calls from an anonymous person in 1998.
The Malicious Calls Bureau is open Monday to Friday and can be contacted at the freephone number 1800 689 689.
PA