Telephone country codes never begin with zero.
Country code +28, which would be dialed as 00 28 from many places, is an invalid code. Country codes +28 and +280 through +289 are unused. There are no valid international telephone numbers beginning with +28.
Country code +8, dialed as 002 8 from many places, is an incomplete code for a country in Asia, or for a transnational telephone service. You need at least one more digit to specify the country.
To avoid confusion, it is best to write an international telephone number in correct international format, beginning with the plus symbol and the correct telephone country code (e.g., +268 or +81), omitting any dialing prefix.
(The plus signmeans "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.)
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.
Fiji has telephone country code +679.
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.
Togo is country code +228.