A Telstra Plus 'Hot Offer' - normally 10k points.
This comes with $80 worth of credit, effectively $100 if you sign up with a referral code (see random generator) in the activation process.
$100 is enough for either 4 monthly cycles of the $25 plan (20GB/month) or a mix of eg 1 month at $25 (20GB) and then 5 months of $15 (3GB/month). Data rolls over so you can start on a $25 plan, downgrade to $15 and still keep the left over data for subsequent months. You have to activate on the $25 plan (as a minimum) to start off with, then you can move down to $15 (the $15 one isn't available for your first month).
I moved 2 members of the household over this way, effectively free phone service for 4 to 6 months depending on your data needs (don't value the 5k points as anything, hence the words 'effectively free'). Another advantage of Belong is that you can data gift (in my case, between plans) and you can either refer a household member as long as you use 2 different email addresses (you can even have them under the same name as long as the email addresses are different).
Don't forget to apply a referral code at checkout!
Edit: these $80 starter packs typically go for $40 (eBay) so a good way to spend your Telstra points from a resale POV as well.
Can activate up to 12mth after purchase, so time to stock up.
Have 20k pts per holiday booking- booked 1d at a time.
Picked up this SIM before for 2000pt free with 2500pts for being vaccinated