Area Code 312 – Colima/Los Tepames, COL

Geographic Coverage and Administrative Jurisdiction

The area code 312 is a geographic National Destination Code (NDC) assigned to the state of Colima, located on Mexico's Pacific coast. It serves the capital city of Colima and the surrounding municipalities, including Villa de Álvarez, Comala, Coquimatlán, and the rural locality of Los Tepames. This NDC falls under the jurisdiction of the Instituto Federal de Telecomunicaciones (IFT), Mexico's telecommunications regulatory body, and is allocated for fixed-line PSTN services, though some VoIP providers also use it for local virtual numbers.

Dialing Formats and Number Structure

Within Mexico, calls to numbers in the 312 area code require the national long-distance prefix 01 followed by the area code and the 7-digit local subscriber number. For example, to call a fixed line in Colima from Mexico City, you would dial: 01 312 123 4567. For international callers, the ITU-T E.164 format applies: dial the international access prefix (e.g., 011 from the US/Canada), then Mexico's country code +52, followed by the area code and subscriber number without the leading '0'. Thus, the same number becomes +52 312 123 4567.

Local and Foreign Caller Instructions

Local callers within the 312 area code can often dial the 7-digit subscriber number directly without the area code, depending on their carrier's local dialing plan. However, for clarity and consistency, it is recommended to always use the full national format. Foreign callers should note that Mexico's numbering plan does not use trunk prefixes in international dialing; the '0' is only used domestically. Additionally, when calling from a mobile phone in Mexico, the national long-distance prefix may be omitted, but the area code must still be dialed.

Overlay and Numbering Considerations

Currently, there is no overlay code for the 312 area, meaning the region is served exclusively by this NDC. However, as demand for telecommunication services grows, the IFT may introduce overlays in the future. Subscribers in Colima may also have numbers from other NDCs if they use mobile services, as mobile numbers in Mexico are non-geographic and begin with different prefixes. For fixed-line services, the 312 code remains the sole identifier for the Colima urban area and its environs.

Practical Usage and Business Implications

For businesses operating in Colima, having a local 312 number establishes a regional presence and can reduce long-distance charges for local customers. VoIP providers often offer virtual numbers with this area code, enabling companies to route calls to any destination worldwide. When listing such numbers internationally, always present them in E.164 format (+52 312...) to ensure proper routing from abroad. Understanding the distinction between national and international dialing is crucial for seamless connectivity.