Country code +1 (dialed as 00 1 from many places) is North America (USA, Canada, etc.).
20 is the first two digits of a three-digit area code. You need the full area code to be specific about what part of North America.
(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 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.
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.
Togo is country code +228.
Liberia is country code +231.