According to the North American Numbering Plan, the area code 526 has yet to be assigned to an area in the US and has been reserved for future use.
526 is the country code for Mexico (52) and covers Band 6 (6). Band 6 includes Altata, Aguascalientes, Celaya, Choix, Culiacan, Durango, Fresnillo, Jalapa, Guamuchil, Zacalecas, La Paz, Baja California, Leon, Los Mochis, Poza, Rica, Queretaro,Quinones, Vaja Ca.s, Silao, Tamazunchale, Tamico, Tam, Tepehuanes and Zacatecas.
To dial out to Mexico from the US, you should dial 011, then 52, then the area code and phone number.
Check out this area code lookup for all US cities or use the area codes locator to find which city a phone area code belongs to at Allareacodes.com.
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