Country code +44 is the United Kingdom, and +44 84 is the start of a non-geographic code, probably a "shared-cost" number. Those numbers may not be reachable from outside the UK, or may be billed at higher rates than calls to ordinary landline numbers in the UK.
(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.
There is no area code 444 in North America (USA, Canada, etc.). Local phone numbers may begin with 444, as in (xxx) 444-xxxx. Mexican area code 444 is San Luis Potosí and surrounding areas. From the United States, dial 011-52-444 for a landline, or 011-52-1-444 for a mobile phone (cellphone), and then the 7-digit local number. Telephone country code +44 is the United Kingdom (England, Scotland, Wales, and Northern Ireland), but there are no numbers that begin with +44 4.
where is telephone country code 1816
That is not a country code.
The country code and area code of Kerki, Turkmenistan is 993, (8)444.
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.