@Quốc Anh Thanks for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.
Azure communication SMS service is available in Australia region and by creating an Alphanumeric Sender ID you will be able to Send SMS from your application.
You can refer to this documentation, for more information about phone number management across different regions and available capabilities in that region.
Currently, we have set of rate limits to send the messages if you want to send more number of messages more than the below values you can send an email to phone@microsoft.com
to increase the rate limits.
Feel free to reach back to me if you have any further questions on this.