Area Code 90 – Mobile Network

Overview of Vietnam's +84 90 Mobile Prefix

The +84 90 prefix is a non-geographic mobile network code assigned to Vietnam's mobile telecommunications landscape. It is one of the oldest and most recognized mobile prefixes in the country, originally allocated to MobiFone, one of the three largest mobile network operators (MNOs) in Vietnam. Over time, due to number portability regulations, subscribers may retain their 90 numbers even when switching to another operator, so the prefix no longer guarantees the current network provider.

Technical Format and Dialing

In the international E.164 format, a Vietnamese mobile number with the 90 prefix is written as +84 90 XXX XXXX. When dialed domestically, the leading trunk prefix '0' is used: 090 XXX XXXX. The total number length is 10 digits when including the trunk prefix '0', or 9 digits after the country code (excluding the trunk prefix). The '90' is the National Destination Code (NDC) for mobile services, and the remaining 7 digits form the subscriber number.

To call a 90 number from abroad, dial your country's international access code (e.g., 00 from most European countries, 011 from the US/Canada), followed by 84, then 90, and the 7-digit subscriber number. For example, a typical number might be +84 90 123 4567. Do not dial the trunk prefix '0' when calling from outside Vietnam.

Regulatory and Operational Details

The 90 prefix is classified as a non-geographic number, meaning it is not tied to any specific region or province. This allows users to retain their numbers when moving anywhere within Vietnam. The numbering plan is administered by the Vietnam Telecommunications Authority (VNTA) under the Ministry of Information and Communications, following ITU-T E.164 recommendations.

Mobile numbers in Vietnam support full voice, SMS, and data services. International SMS and voice calls to +84 90 numbers are routed through standard interconnection agreements. Since the introduction of Mobile Number Portability (MNP) in Vietnam, users can switch operators while keeping their 90 number, which has increased competition among MNOs.

Practical Guidance for Callers

For local callers within Vietnam, always dial the full 10-digit number starting with '0' (e.g., 090 123 4567). For international callers, use the format +84 90 123 4567. Be aware that some VoIP services may require the international format even for domestic calls. Always confirm the number's current operator if you need to contact customer service, as the prefix alone does not indicate the network.