The Illawarra's National Broadband footprint is set to double with NBN Co preparing more than 20,000 premises for connection.
There are already 9300 homes and businesses where the NBN is available - in Kiama and Dapto.
There are a further 10,400 premises in Corrimal, Wollongong and Dapto where crews are already building the fibre network.
NBN Co announced on Thursday that another 24,000 premises had been added to the roll-out map on its website.
These are areas where "build preparation" work is under way - work to make the pits, pipes and exchanges ready for the NBN crews to begin laying fibre.
Suburbs in the north included in this announcement are Corrimal, Tarrawanna, Bellambi, Russell Vale and areas of Woonona east of the Princes Highway. Central areas include Mount Keira, Mangerton, Gwynneville and Coniston. The southern Illawarra suburbs where the early work has started include Horsley, Penrose, Wongawilli and parts of Dapto.
An NBN Co spokesman said the overall construction process would take an average of 12 months before it was ready for people to connect to the NBN.
See the roll-out map on the nbnco.com.au website.