Australian phone numbers vary in format depending on the service type, including landline, mobile, and toll-free. Generally, they consist of a country code (+61), area code (1-2 digits), and a subscriber number (8-10 digits). For example, a Sydney landline number would be 02 9876 5432.

To dial an Australian mobile number domestically, dial 04 followed by the 8-digit mobile number. For instance, if the mobile number is 0412 345 678, you would dial 0412 345 678 directly.

To call Australia from the US, dial 011 followed by Australia's country code (61), and then the local number without the leading 0. For example, to call a Sydney landline (02 9876 5432), you would dial 011 61 2 9876 5432.

Australia's country code is +61. This code is used when making international calls to Australia, and should be added before the local number without the leading zero.

The area code for Sydney, Australia is 02. This two digit code precedes the local phone number when dialing a landline in Sydney from within Australia.

In Australia, 1800 signifies a toll-free number. Calls to these numbers are free for the caller, with the cost borne by the called party. Toll-free numbers typically follow the format 1800 XXX XXX.

Numbers beginning with 190 in Australia are premium rate numbers. These numbers carry additional charges for the caller, and costs can vary depending on the service being accessed.

The ACMA is responsible for regulating Australia's telephone numbering plan. They ensure compliance with international standards, manage number allocation, and oversee any necessary updates to the telecommunications regulations.

Yes, Australia supports mobile number portability (MNP). This means you can retain your existing mobile number even when switching to a different telecommunications provider.

Australian toll-free numbers use the prefix 1800 followed by six digits, for a total of ten digits. For instance, a typical toll-free number would look like 1800 123 456.

The international prefix 0011 should be used when making calls from Australia to other countries. When calling from outside Australia, you should instead use the plus sign (+) followed by 61.

+61 is the internationally recognized country code assigned to Australia by the International Telecommunication Union (ITU). It's a necessary component for routing international calls to Australia correctly.

You can validate Australian landline numbers using the regular expression `^0[2378]\d{8}$`. This regex ensures the number starts with 0, followed by a valid area code (2, 3, 7, or 8), and then eight more digits.