Area Code 66 – Mato Grosso

Overview

The +55 66 area code is a geographic National Destination Code (NDC) assigned to the central and eastern portions of the state of Mato Grosso, Brazil. It serves the state capital, Cuiabá, as well as the major cities of Várzea Grande, Rondonópolis, Sinop, and Barra do Garças. The region is characterized by a mix of urban centers and vast agricultural areas, with the code covering a significant portion of the state's population and economic activity.

Geographic Coverage and Administrative Jurisdiction

This code is managed by the National Telecommunications Agency (ANATEL) and is allocated to the state of Mato Grosso, which is part of the Central-West Region of Brazil. The area code 66 covers a large territory that includes the capital and its metropolitan region, as well as municipalities along the BR-163 and BR-364 highways. It is one of the two geographic codes for Mato Grosso, with the other being 65, which serves the western part of the state, including cities like Cáceres and Tangará da Serra.

Dialing Formats and Caller Instructions

For local calls within the same area code, subscribers dial only the 8-digit local number. For example, to call a landline in Cuiabá from another number in Cuiabá, you would dial 3612-3456. For long-distance calls from other Brazilian area codes, you must dial the national trunk prefix 0, followed by the carrier selection code (e.g., 15 for Vivo, 21 for Embratel), then 66 and the local number. An example from São Paulo (11) would be: 0 15 66 3612-3456.

For international callers, the format is: +55 66 followed by the 8-digit local number. For instance, to call a business in Rondonópolis from the United States, you would dial 011 55 66 3421-1234. When dialing from a mobile phone in Brazil, the same long-distance rules apply, but you may need to include the digit '9' before the local number if calling a mobile line, as Brazilian mobile numbers have 9 digits starting with 9.

Overlay and Numbering Considerations

As of 2024, there is no overlay code for area 66, and the 8-digit numbering scheme remains in place. However, due to increasing demand, ANATEL has implemented a plan to migrate all Brazilian numbers to a 9-digit format for mobiles, which already applies to mobile numbers in this region. Landlines continue to use 8 digits. It is important for callers to verify the correct number length when dialing.

For local callers, remember that calls between different area codes require the full national trunk prefix and carrier code. For foreign callers, always drop any leading '0' from the local number when dialing internationally. This code is also used for VoIP services that provide fixed numbers in the region, following the same dialing rules.