Telephone country codes never begin with zero.
Telephone country code +1, dialed as 00 1 from many places, is North America (USA, Canada, etc.), and 3 is the first digit of a three-digit area code. You need the next two digits to narrow down the location any farther.
Telephone country code +3, dialed as 001 3 from many places, is an incomplete code for somewhere in Europe. You need the next one or two digits to identify the country. For example, +353 is the Republic of Ireland.
To avoid confusion, it is best to write international telephone numbers in correct international format, beginning with the plus symbol and the correct telephone country code (e.g., +1 or +353), omitting any dialing prefix.
(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.)
Telephone country code 0013 is not assigned to any specific country. The International Telecommunication Union (ITU) assigns country codes to different countries for international calling purposes, and 0013 is not part of the standard country code system. It is possible that 0013 is a reserved or special use code for certain telecommunications purposes, but it is not associated with a specific country.
Country code +1 is North America (USA, Canada, etc.). You need the next three digits to be specific.
Leichtenstein is telephone country code +423.
where is telephone country code 1816
That is not a country code.
Gibraltar is country code +350.
Moldova is country code +373.
Slovenia is country code +386.
Togo is country code +228.
Liberia is country code +231.
Angola is country code +244.
Mozambique is country code +258.
Niue is country code +683.
Fiji has telephone country code +679.