Real Companies were actually marketing radio badges VERY akin to Trek combadges to US hospitals five years ago. I haven't heard of any hospitals still using them today, much less as cellphones.
The fundamental problem with this system is, of course, that they display NO IDEA how cell phones work. The magic is not, and has never been, in the handset. It's in the infrastructure.
I know nothing about Aussie wireless telecom. Maybe it has a single nationwide standard for frequencies, encodings, etc. In the US, that varies widely by location and local carriers (though there's enough overlap that most phones mostly work most of the time in most areas where most people mostly are -- ALL those qualifiers, and likely more, are needed for it to be a true statement)