Where is telephone country code 233?

Country code +223 (dialed as 00 223 from many places) is Mali. All numbers have 8 digits after country code +223.

Numbers in the capital Bamako begin with +223 202.

All other landline numbers begin with +223 21.

CDMA wireless numbers (fixed or mobile) begin with +223 44.

Sotelma/Malitel mobile numbers begin with +223 6.

Orange Mali mobile numbers begin with +223 7.

(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.)