The Home Affairs website states that they have a new global call centre, that’s apparently managed by Datacom so you wont be able to get position numbers from staff (Datacom is currently unverified at this stage but information has been supplied to MA).
You can apparently call from anywhere in the world 9am -5pm (local time in the country you’re calling from) on +61 2 6196 0196.
Australian-based callers can still ring the 131881 number but they’ve changed their opening hours to 9am-5pm. If you are inside Australia you can still call the number (02) 6196 0196 and it is answered “Welcome to the Department of Home Affairs. If you need an interpreter…”
Source: https://www.homeaffairs.gov.au/about/contact/make-enquiry