Area Code 231 – New South Wales

Overview of Area Code 231

Area code 231 is a geographic numbering allocation within the Australian National Numbering Plan, specifically serving the state of New South Wales (NSW). It is part of the larger Sydney metropolitan numbering area, which historically used the (02) area code. However, the 231 prefix is not a standalone area code for the entire region; rather, it is an exchange-level prefix within the (02) numbering plan. In practice, callers dial 02 231x xxxx for local and international calls. This prefix is assigned to fixed-line services, including PSTN and VoIP, and is managed by the Australian Communications and Media Authority (ACMA).

Geographic Coverage and Administrative Jurisdiction

The 231 prefix is allocated to the Central Coast region of New South Wales, encompassing areas such as Gosford, Wyong, and surrounding suburbs. This region lies immediately north of Sydney and is part of the Greater Sydney area. The prefix is used for local landline services, and its geographic assignment means that calls to 02 231 numbers are treated as local calls when dialed from other numbers within the same charging zone, which includes most of the Sydney metropolitan area.

Dialing Formats and Instructions

• Local Calls (within Australia): Dial the full national significant number: 02 231x xxxx. The leading '0' is the trunk prefix, and '2' is the area code for NSW/ACT.
• International Calls (from outside Australia): Dial your country's international exit code (e.g., 00 or +), then Australia's country code 61, followed by the area code without the leading '0': 61 2 231x xxxx. Example: +61 2 2310 1234.
• Callers within the same exchange: Even if you are calling from a nearby number, you must always dial the full 10-digit number (including the area code) for all calls, as Australia uses closed dialing plan.

Overlay and Number Portability

The 02 area code is not subject to overlay in the traditional sense, but new numbers are assigned from various prefixes, including 231, as part of the integrated numbering plan. Local number portability (LNP) is available, allowing customers to retain their 02 231 number when switching service providers, provided the service remains within the same geographic area. This means that a number with prefix 231 may be served by a different carrier than originally assigned.

Practical Information for Callers

For businesses and residents in the Central Coast, having a 02 231 number establishes a local presence. For callers outside Australia, it is essential to use the correct international format to avoid misdialing. For example, a caller from the United States would dial 011 61 2 231x xxxx. Always verify the complete number, as the prefix 231 is not a standalone area code; omitting the '2' will result in a failed call.