Country code +1 is North America, including the US and US territories, Canada, and about 17 Caribbean-ish islands. The next three digits are the area code, so you need one more digit to determine where your +1 75X number is located.
Leichtenstein is telephone country code +423.
where is telephone country code 1816
That is not a country code.
The country code and area code of Selby, United Kingdom is 44, (0)1757.
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.