The semi-government owned telco, Telstra, is responsible for the remaining phone booths. In most cases they're found outside or near railway stations & post offices. In the case of most PO ones, they incorporate a Telstra high-speed wi-fi hotspot called Telstra Air which can be used by anyone who uses Telstra/BigPond (aka BigPong) for their broadband supplier and has Telstra Air set up on their home broadband. International users who have Fon accounts can also access these booths.

Telstra Air users have their wi-fi routers automatically configured to add Telstra Air & Fon public hotspots to their routers.
Any data used by such Telstra Air connections are billed to your home broadband allowance, in my case a ridiculously high 1.2 TB per month.

So, as a Telstra Air user, I can park myself near any Air hotspot, be it a public phone booth or another user's router & access broadband via their router at no data allowance cost to said other user.

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