Country code +211 (dialed as 00 211 from many places) is South Sudan.
There are no area codes, per se, in South Sudan.
+211 18 = landlines operated by Sudani
+211 12 = fixed CDMA lines operated by Sudani
+211 16, +211 17, +211 19 = planned ranges for other landline/fixed numbers
+211 91 = mobile operated by Zain
+211 92 = mobile operated by MTN
+211 95 = mobile operated by Vivacel NOW
+211 97 = mobile operated by Gemtel Green
(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 territory of Western Sahara is occupied and controlled by Morocco, so it uses Morocco's telephone country code +212.
'00' is not part of the country code, it is a commonly used international access prefix. Country code +212 is Morocco, and +212 6 is a mobile.
It stands for the telephone area code for Manhattan, NYC. "I was in the 212" means "I was in Manhattan".
Leichtenstein is telephone country code +423.
where is telephone country code 1816
That is not a country code.
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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.