11kV feeder on top the 240/415V consumer mains is normal in this part of the world. In fact I have an 11kV aerial feeder right outside my house, with the 240V house main supply only a few feet below it.
Needless to say, there are insurance claims when the 11kV gets mixed up with the low voltage mains as a result of a car crashing into a pole, or a carbonised possum dangling between the two supplies.
Above ground telephone cables are only seen in a few less densley populated suburbs and then mainly in outlying or rural areas. They share the power poles where available, otherwise Telstra provides the poles.
When cable TV came to Australia in 1995, one of the operators decided to use aerial cables, as is done in the US, and so had to pay for use of the poles which were claimed to be the property of the electricity supplier.
As to what is done when a power pole is replaced, I've seen two things; one is that the pay TV cable is left hanging until the cable operator reattaches it, the other is the old power pole is left in situ, but cut down to just above TV cable.
The other cable operator, pulled their cables through the existing underground phone ducting, often damaging the phone cables.
There was alot of whingeing about the aesthetics of the TV cables to the point where some councils banned them, thus preventing Optus having any pay TV customers in certain areas.
12 years down the track of course everyone has forgotten about the pay TV cables but now have ideas of increasing electricity charges to pay for putting the supply underground.
