Danielle,

this is what i found on the Qantas website. it was in the general section so not specifically domestic or international. So I guess ring and ask is the best option.......

Quote:

Child Restraint Device

The safest way for an infant to travel on an aircraft is in a Child Restraint Device (car seat). Carriage of a lap held infant is allowed however research has demonstrated it does not provide the protection of a child seat.

To purchase a seat for your infant and obtain pre-approval for the use of a child seat contact your local Qantas Office (pre-approval must be obtained a minimum of 24 hours prior to departure).

Note: Approval cannot be obtained on departure at the airport.