Where in North America is area code 427?

There is no area code +1 427 in North America (USA, Canada, etc.).

There is no international telephone country code +427.

Mexican area code 427 (+52 427 for landlines, +52 1 427 for mobiles) serves parts of the states of Queretaro, Mexico, and Hidalgo, including the cities of San Juan del Rio, Polotitlan, and Tlaxcalilla.

(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, and many other countries use different prefixes.)