This deal is for a free 3-month Netflix subscription from activating an Optus prepaid mobile phone or broadband device (via the included sim).
The cheapest Optus phone is the ZTE 286 (same shape as a classic Nokia) for $14.50 - equating to $4.83 per month of Netflix. It's available during this week's catalogue special at Coles. (Image taken from TA's Coles catalogue post)
After buying the phone, activate the included sim (see link above) and Optus will email you a code for the subscription.
The link in OP shows all specials from the catalogue.
Mod: Deal updated with correct dates as per catalogue April 15th to May 12th.
SMS arrived today. Activated it last Saturday. Great deal!