Telephone country codes never begin with zero.
Country code +48, dialed as 00 48 from many places, is Poland, but there are no valid numbers beginning with +48 0. (You must drop the trunk prefix 0 from the Polish domestic area code when putting the number into international format. For example, Warsaw's area code 022 becomes +48 22.)
Country code +80, dialed as 004 80 from many places, is an incomplete code for an international service.
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., +48 or +800), 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.)
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.