Where is telephone area code 083?

0850 may be a valid domestic area code in some country, but it's impossible to say where it is without knowing what country you have in mind.

Country code +850 (dialed as 00 850 from many places) is North Korea.

North American (USA, Canada, etc.) area code +1 850 is Tallahassee and Pensacola, Florida.

(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.)