Where is telephone country code 1 646?

Telephone country code +1 is North America, including the USA, Canada, and various islands, mostly in or near the Caribbean. Telephone area code +1 347 is one of the area codes for New York City, excluding Manhattan.

Manhattan uses area codes 212, 646, and 917. The other four boroughs (Bronx, Brooklyn, Queens, and Staten Island) use area codes 718, 347, 929, and 917.

(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.)