Changes to the cost of calling Non-Geographic Numbers (or NGNs) here will come into force from Sunday December 1.
NGNs are phone numbers beginning with 1800, 1850, 1890, 0818 and 076.
They are often used by businesses, charities, and other organisations to deliver services like helplines, public services and banking.
About 280 million calls are made annually to these numbers.
ComReg said that from December 1 calls from landlines or mobiles to NGNs will cost no more than regular landlines, will be charged per minute and will be included in call bundles.
The regulator said its research shows that 61% of consumers call NGNs reluctantly, while 86% of consumers are not able to estimate the cost of calling them.
It said that confusion around NGNs runs deep and despite 1800 NGNs being free to call (called "Freephone"), 37% of consumers thought that the caller pays to call these numbers.
"We saw a real issue with the way NGNs were perceived by Irish consumers, who were avoiding using these contact numbers over fears of high costs and worrying about what impact this would have on their phone bill," commented Garrett Blaney, Commissioner at ComReg.
He said to address these concerns, both ComReg and telecoms operators have worked extensively together over the last number of months to introduce measures to improve NGNs in Ireland.
"The introduction of this new charging regime for calling these phone numbers is the first step towards creating a system that consumers can trust and have greater confidence in using," he added.