Fiji is country code +679. There are no city codes or area codes. The local number is 7 digits.
(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, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
Fiji has telephone country code +679.
Unlike the Pacific islands that are owned by the United States, Fiji is not part of the North American Numbering Plan, so it doesn't have an "area code". Its country code is +679.
Leichtenstein is telephone country code +423.
where is telephone country code 1816
That is not a country code.
Country code +57 is Colombia.
Country code 52 is Mexico.
Gibraltar is country code +350.
Moldova is country code +373.
Slovenia is country code +386.
Vanuatu is country code +678.
Niue is country code +683.