Area Code 631 – Nogales, SON

Geographic Coverage and Administrative Jurisdiction

The area code 631 is a geographic National Destination Code (NDC) assigned to the city of Nogales and its surrounding metropolitan area, located in the state of Sonora, Mexico. This code serves the northern border region adjacent to the United States, specifically the city of Nogales, Arizona. The jurisdiction includes the municipality of Nogales and several nearby localities, such as Ímuris and Magdalena de Kino, which rely on the same numbering plan area for their fixed-line and mobile services.

Dialing Formats and Caller Instructions

When dialing a number within the 631 area code from within Mexico, the national trunk prefix 0 is typically used before the area code, followed by the seven-digit local number. The complete national format is: 0 631 XXX XXXX. However, for calls originating from a mobile phone within Mexico, it is common to omit the trunk prefix and dial directly: 631 XXX XXXX.

For international callers, the correct format is: +52 631 XXX XXXX. For example, to call a business in Nogales from the United States, you would dial 011 52 631 123 4567 (or simply +52 631 123 4567 from most mobile devices). It is essential to include the country code and area code without any leading zeros.

Overlay Considerations and Numbering Plan

As of the latest ITU-T E.164 updates, the 631 area code does not have an overlay code. All fixed-line and mobile numbers within this region share the same seven-digit local number pool. This means that local calls within the area code are dialed using only the seven-digit number, without the area code, when calling from a landline in the same geographic region. However, due to the increasing demand for numbers, the Mexican Federal Telecommunications Institute (IFT) may introduce an overlay in the future, which would require ten-digit dialing for all local calls.

Services and Usage

The 631 area code is used for both fixed-line (PSTN) and mobile services. Mobile numbers in this region are assigned to various Mexican mobile network operators (MNOs) and mobile virtual network operators (MVNOs). It is important to note that mobile numbers are non-geographic in nature, but they are allocated within the 631 numbering plan for administrative purposes. When calling a mobile number in the 631 area code, the same dialing rules apply as for fixed lines.

For businesses and residents in Nogales, the area code is a critical part of their identity, especially for cross-border commerce with the United States. The proximity to the border makes this area code particularly relevant for companies that operate on both sides of the border, and understanding the correct dialing procedures is essential for seamless communication.