Here's how to check how many international call minutes you have remaining to call landlines in Australia.
If you're on the USA Extreme or USA Max plan: dial *777*5# on your phone keypad and press call.
If you're on the USA Saver, USA Daily or USA Budget plan: dial *777*4# on your phone keypad and press call.
Your remaining minutes balance will be messaged to you (example below is on an iPhone). Do not be alarmed that it says "Mexico Plus Long Distance Minutes" - the International Call Pack is targeted to people calling Mexico, but the minutes also apply to calls to landlines in Australia.
