Could there be other iPhone apps that get classed as ‘browsing”?
From a technical standpoint I'm struggling to understand how Optus can give any reliable breakdown of usage at all. I've seen a few post in the past of people struggling to make sense of the usage breakdown that the Optus app provides, so I find those breakdowns useless at best and misleading at worst.
Because almost everything these days goes over HTTPS which is a secure protocol, Optus can't actually look inside the data being used by you to determine the classification. They generally only have two bits of info they can use 1] The domain name (i.e. site name), or 2] port number (basically the specific pipe the data should travel through).
So any combination of domain & port number can be used to "guess" at what type of data is being sent, but its far from accurate.
For example, HTTPS browsing will use port 443 so anything that uses port 443 might be "logically" classifiable as browsing, but youtube (as far as I can tell) also send its videos through 443, not just its web pages, so anything from the youtube.com domain will largely be videos. So which guess does Optus use? Who knows.
Sorry about the late reply - I had to wait for my new month's quota before experimenting with my Netflix + hotspot. Yes, you are right. Using Netflix on my smart TV hot-spotted to my Optus mobile phone does go through as un-metered. I also think I have found the answer to my excess data usage. My computer is also normally hot-spotted to my phone, and although i had my phone set to avoid any software updates when it was using mobile data, my computer (MacBook) does not seem to know that a hot-spot is not broadband and so was auto-updating during the night. I have since turned off auto-update on my computer.
my computer (MacBook) does not seem to know that a hot-spot is not broadband and so was auto-updating during the night.
That is normal behaviour.
Generally speaking, only the device that established the internet connection knows what type of connection that is (i.e. mobile or fixed line). Every other device that connects to it has to assume that its just a standard network connection.