Tropo has Australian numbers. And 40 other countries. Has for years. http://tropo.com (disclosure, I'm the product manager).
But really, if all you're doing is dialing out, then you don't actually need a local number. Just use whatever service you want (us, Twilio, Plivo, someone else, etc) and set the caller ID to a local number or make the call as a blocked caller ID.
But really, if all you're doing is dialing out, then you don't actually need a local number. Just use whatever service you want (us, Twilio, Plivo, someone else, etc) and set the caller ID to a local number or make the call as a blocked caller ID.