The nuisance calls, in which an unknown number calls and immediately hangs up in an effort to trick the receiver into returning a long-distance international call, thereby incurring a hefty charge, are sometimes referred to as Wangiri scams.
The calls in question often involve connection to an answering machine on a premium rate line.
They will be filtered by TDC to protect as many customers as possible.
TDC has declined to give detail on how the filter will work, but it will function automatically and prevent 90 percent of the unwanted calls, according to the company. The method has been undergoing testing since November.
Previously, TDC has encouraged customers to report such calls so it can block nuisance numbers individually.
The new filter will be available to all customers of TDC Group, including subsidiary companies TDC, YouSee, Telmore and Fullrate – encompassing as many as three million people.
YouSee director Jacob Mortensen said the number of calls of this type has proliferated “a lot”.
“We have seen up to two million calls per month amongst our customers. This is where we have put a filter in place. That will ensure (the calls) never reach customers,” Mortensen said.
Although it is confident in the filter, TDC maintains its advice for customers not to return calls to unknown numbers, unless the caller leaves a message identifying themselves.