Homes in Cork, Cavan and Galway will be connected to the National Broadband Plan network by the end of the year.
Work on the new fibre network is to start in Cork and Cavan by the end of the month, with townlands in Galway to follow shortly.
National Broadband Ireland has also confirmed that minimum download speed for the network has increased to 500 megabits per second.
Under the contracts signed in November, the original commitment was to provide 150Mbps to every person and business in the Intervention Area.
The group's chief executive, Peter Hendrick, says the plan is to have homes in Cork, Cavan and Galway able to access this high-speed internet by the end of 2020
Mr Hendrick says "That's the plan and we will start to build over the coming weeks."
"We would expect that disruption would be minimal, no different than typical telecoms build programme. We are utilising a lot of the existing infrastructure that is in place, so it should be a speedy network build with minimal disruption".