Qantas Frequent Flyer - What is I Class fare ?

I am connecting in SYD to UA in June in what appears to be QF I class from BNE.

It gets a business class seat.

I'm guessing it is below Z in the pecking order.

Have any posters had experience with this fare basis?

I am particularly interested to see if flights can be changed on the day of flight to another one with the same fare basis.

The fare rules of the particular ticket determine how changeable the ticket is - not whether it books into I class. But, yes, I class is about as low as you can go - if QF prioritises based on fare bucket class.

I currently have I class tickets SYD-LHR-xxx as part of the recent companion fare promo. It booked into I class and the fare rules posted on the web at time of purchase said "upgradable..." but when trying to request the upgrade on the web, the computer said not eligible for upgrades. This will need a phone call to sort out.

... This will need a phone call to sort out.I believe having to call is normal for I class with qantas.

It is upgrade eligible.

"I" business fares are definitely bookable via the website, where they are listed as "Business exclusive"; I have recently done just such a booking myself. They used to be strictly occasional "specials", but now seem to be permanent features of the fare spectrum.

Thank you for that.
Can I change to another flight on the day of travel if I class seats are available and is there a fee?

I class is a cheap business class bucket. It can be booked through travel agents as well as online.

Whether an I fare can be changed depends on the particular fare basis, as does the fee. For example, at the moment an I class ticket from London to Sydney can't be changed at all, from Sydney to London can be changed at $300 penalty, and from Sydney to Bangkok it's $150.