+421 is the country code for Slovakia. Substitute your international dialing prefix for the plus sign. Thus, from most of Europe, dial 00 421; from the US and Canada, dial 011-421; from Australia, dial 0011 421.
(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, and many other countries use different prefixes.)
Kosovo has not yet been assigned its own separate telephone country code. Landline numbers continue to use Serbia's country code +381, with area codes 28, 29, 38, and 39. Mobile numbers from Kosovo use country codes +377 (Monaco) and +386 (Slovenia) on an interim basis.
(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.)
Czechoslovakia was country code +42 until the country split into two countries. The Czech Republic is now country code +420, and Slovakia is now country code +421.
The country code and area code of Bytca, Slovakia is 421, (0)41.
The country code and area code of Kosice, Slovakia is 421, (0)55.
The country code and area code of Prievidza, Slovakia is 421, (0)46.
Leichtenstein is telephone country code +423.
where is telephone country code 1816
That is not a country code.
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.
Liberia is country code +231.
Angola is country code +244.
Mozambique is country code +258.