Good day, @BBYRNE.

Thanks for following the recommended steps that were shared above. I'm here to you in accessing your QuickBooks account.

I can see that you've posted your concern in QuickBooks Community for Australia. To verify the issue, let me ask you a few questions so I can provide you the right solution.

Are you using the QuickBooks Online Australia version? 

If so, you have to use a mobile phone number that is registered for this country to open the account. This way, your accountant could connect to the application. 

This can be also the reason why you're getting the error "Country code not supported for sending text messages". To clear this out, make sure to use a phone number with the same area/country code as your QuickBooks version.

If your business is located in Ireland, you can subscribe to QuickBooks Online Ireland version instead. This way, you can use an Ireland mobile number to verify your account. 

As always, feel free to visit our QuickBooks Community help website if you need tips and related articles in the future.

Keep in touch if you need any more assistance with this, or there's something else I can do for you. I've got your back. Have a good day.