Telephone country code +52, dialed as 00 52 or 011 52 from many places, is Mexico.
Landlines and mobile phones use the same geographic area codes. However, to dial a mobile number in international format, you insert the prefix '1' between country code +52 and the geographic area code. For example, a landline number in Guadalajara begins with +52 33, but a mobile in Guadalajara begins with +52 1 33.
Area code 33 is Guadalajara.
Area code 55 is Mexico City.
Area code 81 is Monterrey.
All other area codes are three digits, in the range 200 - 999.
(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.)
Country code 52 is Mexico.
The telephone country code for Vietnam is +84. The area code for Quang Binh is 052, or +84 52 in international format.
The telephone country code for Zimbabwe is +263. The area code for Guruve is 058, or +263 58 in international format.
Leichtenstein is telephone country code +423.
where is telephone country code 1816
That is not a country code.
Country code +57 is Colombia.
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.