There are no telephone country codes beginning with zero. Country codes beginning with 2 are mostly in Africa, except for +297, +298, and +299, which are in random places.
For more information about country codes beginning with +2, see the related question.
Telephone country codes never begin with zero.
Country code +20, dialed as 00 20 from many places, is Egypt, and area code +20 2 is Cairo.
To reduce the possibility of confusion, it is best to write an international telephone number in correct international format, beginning with the plus symbol and the correct telephone country code (in this case, +20), omitting any dialing prefix.
(The plus signmeans "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 is00, but North America (USA, Canada, etc.) uses 011, Japan uses010, Australia uses0011, and many other countries use different prefixes.)
Telephone country codes never begin with zero.
The most commonly used international access prefix is 00, which would leave country code +02, which is an invalid code.
Some places use 000 as the international access prefix, which would leave country code +2, which is an incomplete code. Most country codes beginning with +2 are in Africa, but you need one or two more digits.
Telephone country codes never begin with zero.
If your international access prefix is 00, then you are asking about telephone country code +020, which does not exist.
If your international access prefix is 000, then you are asking about telephone country code +20, which is Egypt.
To prevent this sort of confusion, it is best to always quote an international telephone number beginning with the plus symbol and the country code, omitting any access prefix, since different countries use different prefixes.
(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 +20 is Egypt, and a number beginning with +20 12 is a mobile on the Mobinil network.
Telephone country codes never begin with zero.
Africa
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.