I believe they can do it. They can also do it over the phone in advance. I think that they now charge for the service and is more expensive than just going to the online site
Personally, I wouldn't recommend waiting until you get to the airport in case it issues you a referral number rather than an ETA. I have seen a referral be issued once before which involved contacting Australian High Commission during normal business opening hours to get it agreed. Not something I'd want to risk at the airport
Get paid up to 25% in real cash from your everyday purchases from leading companies such as Virgin Australia, Booking.com, Woolworths, Coles, Apple, Microsoft and much more. Free to join and no catches!