Due to diverse technological and network capabilities, attempting to call a 1300 number from overseas doesn't guarantee success for all countries.
While countries like the USA, UK, New Zealand, Hong Kong, and Singapore usually support these calls, success rates vary widely.
You might struggle more in places like South America due to different technology and network services.
To be sure, you'll want to check with your provider, as not all countries can connect to Australian 1300 numbers.
You have to worry about more than just getting the correct number.
Make sure that you've considered these things so that your overseas call has the best chance of connecting.
Australia has three main time zones that all differ considerably from Europe and the Americas. Australian Western Standard Time (AWST): UTC +8:00, Australian Central Standard Time (ACST): UTC +9:30 and Australian Eastern Standard Time (AEST): UTC +10:00.
You'll also have to factor in that some states use daylight saving time from October to April when the clocks move forward an hour. If in doubt, Google the current time in the location you are calling.
This makes sure that you're calling at a time when the office is going to be opening. You don't want to be spending money connecting to a call that's not going to get through to a person.
Australia has seven national public holidays a year and state-specific holidays on top of that. During these public holidays, most businesses will be closed. If your call isn't getting through, then check that you're not trying to call on a public holiday.
As well as knowing the timezone you should also check the business hours. While some large companies might have a 24-hour call centre, smaller businesses will only operate during standard business hours.
There isn't a standard rate at which your call will be charged as each provider sets their rates. But, you should be aware that it's likely going to be higher.
While a 1300 number is normal for most businesses to use inside of Australia, it's possible that they also have a more international friendly option. It's worth searching for the company to see what other numbers are available as these might have a higher chance of connecting and cost less. You could also reach out to their support team first if time isn't of the essence.