Area Code 855 – Bakers Hill/Bindoon/Bullsbrook East/Byford/Dwellingup/Gidgegannup/Gingin/Guilderton/Mandurah/Mount Helena/Mount Wells/Pinjarra/Rockingham/To...

Overview of Area Code +61 855

Area code 855 is a geographic National Destination Code (NDC) within the Australian telephone numbering plan, as administered by the Australian Communications and Media Authority (ACMA) under the ITU-T E.164 standard. It is assigned to a diverse set of localities in the state of Western Australia, primarily serving the Peel region and parts of the Wheatbelt and Perth metropolitan fringe. The code covers towns and suburbs including Mandurah, Rockingham, Pinjarra, Dwellingup, Gingin, Guilderton, Bindoon, Bakers Hill, Gidgegannup, and Mount Helena, among others.

Geographically, this code spans from the Indian Ocean coast (Guilderton) to the Darling Scarp and inland agricultural areas. It is important to note that while some of these locations are within the greater Perth metropolitan area (e.g., Rockingham), the code is distinct from the Perth metropolitan codes (2, 3, 4, 5, 6, 7, 8, 9) and is used for specific exchanges.

Dialing Format

When dialing a number within Australia, the full national significant number includes the leading trunk prefix 0, followed by the area code and the local subscriber number. For example, a local number in Mandurah might be (08) 8550 1234. Internationally, callers must use the country code +61, drop the leading zero, and dial +61 8 8550 1234. The area code is part of the NDC and is mandatory for all calls, including local calls, as per the Australian 10-digit dialing plan.

Local and International Caller Instructions

• Local callers within the 855 area should still dial the full 10-digit number (including area code) to ensure proper routing, as overlay and mobile number portability require unambiguous dialing.
• International callers should dial +61 8 8550 1234 (replacing the leading zero of the area code with the +61 country code).
• Callers from other Australian regions dial 08 8550 1234.

Regulatory and Technical Notes

The code is allocated to Telstra and other carriers for fixed-line services, but due to Local Number Portability (LNP), the subscriber may be served by any provider. The area code is part of the Australian Numbering Plan and is used for both PSTN and VoIP services, though VoIP numbers may not be geographically tied. The region has seen growth due to population expansion in Mandurah and Rockingham, leading to increased demand for numbers. No overlay has been implemented for this code as of the latest ACMA updates, but future changes are possible.