Area Code 81 – Mobile Network

Overview of Vietnam's +84 81 Mobile Prefix

The +84 81 prefix is a non-geographic mobile network code assigned within Vietnam's national numbering plan, as administered by the Vietnam Telecommunications Authority (VNTA) under the Ministry of Information and Communications (MIC). Unlike geographic area codes that correspond to specific provinces or cities, the 81 prefix is allocated to mobile services, meaning it is not tied to any particular region. Subscribers using numbers beginning with 81 can be located anywhere in Vietnam, and the prefix does not indicate the caller's or callee's physical location.

Numbers under the 81 prefix are part of Vietnam's closed dialing plan. The full national significant number (NSN) consists of 9 digits, starting with the prefix 81 followed by 7 additional digits. Therefore, a typical mobile number in Vietnam is formatted as 081X XXX XXX when dialed domestically, and +84 81X XXX XXX when dialed from abroad. It is important to note that the leading '0' is a trunk prefix used for domestic dialing and is not included in the international format.

Dialing Formats and Examples

To call a Vietnamese mobile number with the 81 prefix, the dialing procedure varies depending on the caller's location:

• Domestic call (within Vietnam): Dial the full 10-digit number including the trunk prefix '0'. For example, if the subscriber number is 812 345 678, you would dial 0812 345 678.
• International call (from outside Vietnam): Dial the international access prefix (e.g., 00 from most countries), followed by Vietnam's country code +84, and then the 9-digit NSN without the leading '0'. For the same number, you would dial +84 812 345 678.

This format applies to both voice calls and SMS. When sending an SMS internationally, the recipient's number should be entered in the same international format: +84 812 345 678.

Regulatory and Technical Aspects

The 81 prefix is used by mobile network operators (MNOs) and mobile virtual network operators (MVNOs) that have been granted licenses by the MIC. The allocation of prefixes is managed to ensure efficient use of numbering resources. Mobile number portability (MNP) is implemented in Vietnam, allowing subscribers to retain their numbers when switching operators. However, the prefix does not necessarily indicate the current operator; it reflects the original allocation. For routing purposes, the prefix is used to identify the network, but after porting, calls are routed based on a central database.

All mobile numbers in Vietnam, including those with the 81 prefix, are considered non-geographic and are part of the public switched telephone network (PSTN) and integrated with VoIP and mobile networks. The numbering plan supports both voice and data services, and the 81 prefix is not reserved for any specific service type beyond mobile communications.

For businesses and individuals, understanding the correct dialing format is essential to ensure successful connectivity. Whether you are a local resident or an international caller, using the proper international prefix and country code will connect you to the intended mobile subscriber in Vietnam.