The cache is not at the listed coordinates, but is within a couple of kilometres.
Near the listed coordinates, and at other places along the Blackall-Adavale Road, you may notice timber poles with insulators fixed to the tops. These once supported telephone lines, providing telecommunication across the district. But the old copper wires are now long gone, replaced by microwave dishes, mobile towers, satellites and underground cables.
The cache can be found at S24 44.XXX E145 18.XXX.
The numbers missing from the final coordinates can be determined using the following phone numbers.
(05) 8974 1479 131 7964 9805 8741
3971 3654 131 4697 1300 321 123
Despite there being no mobile phone coverage, this will work from the listed coordinates (or anywhere else without phone coverage). Give it a try!
Good luck!