If you are like me and you have totally wiped all your carrier's bloatware, for which Telstra has a LOT, you might still want an easy way to check on your pre-paid balance.
The easy way is to dial #100# on your device.
Even better way is to create a contact for Telstra Pre-Paid Balance with #100# as the number. Then add this as a shortcut to your desktop as a "Direct Dial" custom shortcut.
Hope you find this useful.