The communications regulator says introducing 5G for internet access would not meet the needs of everyone living in rural Ireland.
Comreg is appearing before the Oireachtas Communications Committee to outline its position on the controversial National Broadband Plan.
Questions are being asked about why the State is spending over €3bn on fibre broadband when new mobile 5G technology is shortly to become available.
However, ComReg Commissioner, Jeremy Godfrey, says it wouldn't be viable for the entire country.
"In order to provide the capacity, if everyone in the coverage area was every evening was watching streaming video, that would be another kettle of fish entirely," he said.
"Even that very expensive additional mobile network coverage wouldn't be sufficient to meet the objectives of the NPB."