Area Code 878 – Piedras Negras, COAH
The phone area code for Piedras Negras, COAH is 878 (international format +52878). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 878
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Piedras Negras, COAH
Overview of Area Code 878
Area code 878 is a geographic numbering plan area (NPA) within the Mexican national numbering plan, assigned to the city of Piedras Negras and its surrounding municipalities in the state of Coahuila (COAH). This region is part of the northern border area of Mexico, adjacent to the U.S. state of Texas, and is served by the PSTN (Public Switched Telephone Network) and modern VoIP services.
Geographic Coverage and Administrative Jurisdiction
The 878 area code covers the municipality of Piedras Negras, including the urban area and nearby localities such as Villa de Fuente, and extends to adjacent rural communities. Administratively, it falls under the jurisdiction of the state of Coahuila, and the local regulatory authority is the Instituto Federal de Telecomunicaciones (IFT). The region is economically significant due to its border trade and manufacturing (maquiladora) industry.
Dialing Formats and Instructions
For local calls within the 878 area code, the national dialing format is used: 878 XXX XXXX (10 digits). However, when dialing from a mobile phone, it is common to prefix the national long-distance code '01' when calling from another area code within Mexico. For international callers, the format is +52 878 XXX XXXX.
Example: To call a landline in Piedras Negras with the number 123 4567, you would dial:
- From within Piedras Negras (local): 878 123 4567 (if using a landline, some operators may require the area code even for local calls; check with your provider).
- From another Mexican city (e.g., Mexico City): 01 878 123 4567 (national long-distance).
- From the United States or any other country: +52 878 123 4567.
Overlay Considerations and Numbering
Currently, there is no overlay code for the 878 area; it remains the sole geographic code for Piedras Negras. However, due to the growth of mobile and VoIP services, number portability is in effect, allowing users to retain their numbers when switching providers. The 878 code is used for both fixed-line and some mobile services, but mobile numbers are non-geographic and typically start with a 3-digit mobile prefix (e.g., 878 is not a mobile prefix; mobile numbers in Mexico are assigned separate codes like 878 is not used for mobile).
Practical Guidance for Callers
When calling a Piedras Negras number from abroad, always use the full international format, omitting the leading '0' of the national trunk prefix. For local callers, be aware that some businesses may list numbers in the 8-digit format (e.g., 123 4567) without the area code; in such cases, you must add the area code if you are outside the local area. For VoIP users, ensure that your provider supports E.164 formatting and that you include the '+52' country code when saving contacts for international use.