Country code +52 (dialed as 00 52 or 011 52 from many places) is Mexico.
Mexico City is area code 55.
Guadalajara is area code 33.
Monterrey is area code 81.
All other area codes are three-digit numbers in the range 200 through 999.
Mobiles use the same geographic area codes as landlines, but add the prefix '1' between country code and area code. For example, a landline in Guadalajara begins with +52 33, but a mobile from Guadalajara begins with +52 1 33.
(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.