Telstra Wholesale have been working on a Federal Government initiative called the Mobile Black spot Program.
This initiative is building approximately 500 base stations to improve mobile coverage in specific poor or no-coverage areas. 429 of these base stations will be built by Telstra.

Check this Telstra website if you want to understand a bit more about this initiative and find out where is your nearest black spot site.

There were 51 base stations already built and automatically added to our 4G Prima Mobile service in August 2016, which increased our coverage to 98.8% of the Australian population, and there are still many more to be built.

These changes are automatic and nothing needs to be done to take advantage of the increased 3G and 4G coverage areas. The following sites have had their coverage increased in August:

Table provided by Telstra Wholesale