Mauritius is country code +230. There are no area codes. The local number is 7 digits, except for mobile numbers which are 8 digits beginning with '5'.
(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.)
Maldives is country code +960.
The country code starting with 894 is assigned to the Maldives. This code is used for international dialing purposes when making phone calls to the Maldives from abroad.
Leichtenstein is telephone country code +423.
where is telephone country code 1816
That is not a country code.
Fiji has telephone country code +679.
Country code +57 is Colombia.
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.