How do you call a west African number from a UK landline?

Answer 1

You need to know the country code (+2XX) and phone number.

(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.)

The international access prefix from the UK is 00.