The numbers in a telephone country code identify the country or the transnational telephone service that you are calling. Telephone country codes can be one digit (+1 for North America, including the USA, Canada, and some nearby islands, or +7 for Russia and Kazakhstan, formerly for the whole USSR), two digits, or three digits. They are grouped into geographic zones, as follows:
There are several exceptions to those general rules.
There is no country code +530, and there are no valid numbers beginning with +53 0. (Country code +53 is Cuba, but no Cuban numbers begin with 0.)
Country code +66 is Thailand. Numbers beginning with +66 8 are mobiles.
61 is the Country Code for Australia, but no Australian phone Area Code numbers begin with a 6, so no numbers will begin 61642...
Country code +34 is Spain, but there are no numbers beginning with +34 1.
Country code +43 is Austria. Although mobile numbers begin with +43 6, so do some landline numbers.
Macau is country code +853. There are no area codes within Macau. Most numbers are 8 digits after the country code +853. Most ordinary landline numbers begin with +853 2. Direct dial-in numbers begin with +853 8. Most mobile numbers begin with +853 6.
Bhutan is country code +975. Mobile numbers begin with +975 17.
Greece is country code +30. Landline numbers in Greece begin with +30 2.
Country code +699 is unassigned. There are no valid international numbers beginning with +699.
The country code is France +33, and numbers beginning with +33 7 are mobile phones.
Niger is country code +227. Landline numbers begin with +227 20. Fixed wireless numbers begin with +227 21. Mobile numbers begin with +227 9.
invalid code Telephone country code +7 is Russia and Kazakhstan, but there are no valid numbers beginning with +7 0.