We used to use a service called VNG transmitted out of Lyndhurst in Victoria, it was similair to the WWV that the yanks have on HF, information as in the link
http://tufi.alphalink.com.au/time/nsc_vng_leaflet.pdf
It was shutdown in 2002, timing is done now by using the GPS network and this is what the NextG mobile phone tarnsmitters use as their time refernce.
So when you go from state to state thats how the phone always adjusts itself as it refrences to the phone network.