'00' is not part of the country code, it is a commonly used international access prefix. Country code +256 is Uganda, and +256 78 is a mobile.
Gabon is country code +241.
Country code +256 (dialed as 00 256 from many places) is Uganda.Landlines served by UTL all begin with +256 4.Landlines served by MTN begin with +256 3.Other landlines begin with +256 20.Mobile numbers begin with +256 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.)
The country code and area code of Aydin, Turkey is 90, (0)256.
The country code and area code of Arua, Uganda is 256, (0)476.
The country code and area code of Gulu, Uganda is 256, (0)471.
The country code and area code of Kabale, Uganda is 256, (0)486.
The country code and area code of Lira, Uganda is 256, (0)473.
The country code and area code of Masaka, Uganda is 256, (0)481.
The country code and area code of Masindi, Uganda is 256, (0)465.
The country code and area code of Mbarara, Uganda is 256, (0)485.
The country code and area code of Mityana, Uganda is 256, (0)36.