Telephone country codes never begin with zero.
Country code +1, dialed as 00 1 from many places, is North America (USA, Canada, etc.), and area code +1 760 is part of Southern California, USA, including Death Valley, Palm Springs, Calexico, Escondido, Oceanside, Ridgecrest, Victorville, and a small part of San Diego. It stretches from northern San Diego County to the eastern Sierra Nevada mountains. Area code +1 442 is an overlay on area code 760, serving the same communities.
Country code +7, dialed as 001 7 from many places, is Russia and Kazakhstan. Numbers beginning with +7 6 are reserved for Kazakhstan, but are not currently in use.
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., +1 or +7), 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.
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.