Telephone country code +44 is the United Kingdom, and a number beginning +44 777x is a mobile phone.
(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.)
The telephone code 44777 is not a country code but rather a mobile phone number prefix used in the United Kingdom. In the UK, numbers starting with 447 are typically mobile numbers that begin with the international dialing code for the UK, which is +44. The specific format of 44777 indicates a mobile service provider.
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.