Where in North America is area code 810?

Answer 1

North American area code +1 810 is in Michigan, including Flint, Port Huron, and the suburbs on the northeast side of Detroit.

(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 Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)