Area Code 21 – Mobile Network
The phone area code for Mobile Network is 21 (international format +6421). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 21
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Overview of New Zealand Mobile Prefix 21
In the New Zealand telecommunications numbering plan, the prefix 21 is a non-geographic code allocated to mobile network operators (MNOs) and mobile virtual network operators (MVNOs). Unlike geographic area codes that correspond to specific regions, the 21 prefix is used exclusively for mobile services, enabling number portability across different carriers. The full national significant number (NSN) for a mobile subscriber is typically 8 to 9 digits, starting with the prefix 21 followed by a 6- or 7-digit subscriber number (e.g., 21 234 5678).
Dialing Formats
When calling a New Zealand mobile number with the 21 prefix from within the country, you must dial the national trunk prefix 0 before the NSN. For example, a local caller would dial 021 234 5678. From overseas, callers must use the international access code, followed by New Zealand's country code +64, and then the NSN without the leading zero. Thus, the same number would be dialed as +64 21 234 5678. It is essential to omit the leading '0' when dialing from abroad to avoid routing errors.
Number Portability and Routing
New Zealand implemented mobile number portability (MNP), allowing subscribers to retain their 21-prefixed numbers when switching between mobile operators. As a result, the prefix does not indicate a specific carrier; it is a generic mobile identifier. Routing is determined by a central number portability database, ensuring calls and SMS messages are correctly delivered regardless of the current network operator.
Usage and Services
The 21 prefix is used for voice calls, SMS, MMS, and mobile data services. It is also used for machine-to-machine (M2M) communications and IoT devices that require mobile connectivity. Because it is a mobile code, it is not tied to any geographic location, making it suitable for nationwide services and nomadic use.
Regulatory and Technical Notes
The allocation of the 21 prefix is managed by the Commerce Commission under the Telecommunications Act. The numbering plan follows ITU-T E.164 recommendations, ensuring global interoperability. For international callers, it is important to note that New Zealand's country code is +64, and the 21 prefix is part of the national destination code (NDC) for mobile services. When storing numbers in international format, always include the '+' sign and country code, and omit any leading zeros.