Country code +377 (dialed as 00 377 from many places) is Monaco.
(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.)
Serbia is country code +381.You must drop the trunk prefix '0' from the beginning of the Serbian number when calling from other countries. For example, Belgrade's area code 011 becomes +381 11.Mobile numbers begin with +381 6.Mobile numbers in the disputed region of Kosovo begin with +377 44, +377 45, +386 43, or +386 49. (Country code +377 is Monaco; country code +386 is Slovenia.)
The country code and area code of Cocula, Mexico is 52, (01)377.
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 Nanyang- HEN, China is 86, (0)377.
There is no 909 country code.
There is no telephone country code +897, nor +89, nor any other country code beginning with +89. There are no valid telephone numbers beginning with +89.
Gibraltar is country code +350.
Moldova is country code +373.
Slovenia is country code +386.
Togo is country code +228.