Australian Constitution - Section 69 - Transfer of certain departments
On a date or dates to be proclaimed by the Governor-General after the establishment of the Commonwealth the following departments of the public service in each State shall become transferred to the Commonwealth:-Posts, telegraphs, and telephones:
Naval and military defence:
Lighthouses, lightships, beacons, and buoys:
But the departments of customs and of excise in each State shall become transferred to the Commonwealth on its establishment.