Some 10,000 people are contacting their phone firms every month, asking them to prevent direct marketing companies from contacting them.
Since July 21st all telephone subscribers have the right to opt out of receiving these "cold calls".
Some 125,000 people had availed of this option up to February 1st, and requests had recently been averaging 10,000 a month, according to telecommunications regulator ComReg. With 1.6 million fixed telephone lines in the State, this represents about 8 per cent of customers.
Phone subscribers can register their preference to opt out of direct marketing calls by contacting their phone company.
This will be recorded in the National Directory Database, a central record of all telephone numbers listed in phone books or available from directory inquiries. It may take up to five working days to put the ban in place because of the large number of requests received. Marketing companies that ignore this opt- out can be prosecuted by the Data Protection Commissioner.
People with ex-directory numbers cannot ask to opt out as their numbers are not listed in the database, but ComReg has advised ex-directory number-holders who do not want such calls to instruct the callers to remove their number from their database.
The issue does not arise for mobile-phone users, as all mobile telephone numbers are automatically barred from unsolicited marketing calls.
The Data Protection Commissioner's Office worked with ComReg to launch the move after noting the high number of complaints it had received.
Seán Sweeney, senior compliance officer with the Data Protection Commissioner's Office, said half the complaints his office received about marketing concerned telemarketing.
He expected the number of people opting out to increase.
"It's a reasonable number, but we would like to see it higher," he said. "We would have expected it would be higher, given the level of complaints to our office."
Phone firms have been including details of this new option in their billing mailshots recently, and the Data Protection Commissioner is considering whether this information should be a permanent fixture on every bill.
Mr Sweeney said his office would be holding a publicity campaign later this year.
