Two options:

Have you tried not putting in any apns or settings ? Usually for safcom, it works without the need for settings; 
(a wildcard redirection is most likely configured).

However, if you must:

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You can feed in the settings manually:

apn: safaricom
username: saf
password: saf  (or web) (or dont put password)

You may also just put the apn and ignore username and password; because most likely its set to accept a wildcard;

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Another option that works is:

apn: web.safaricom.com
username: web
password: web  (or saf) (or dont put password)


You may also just put the apn and ignore username and password; because most likely its set to accept a wildcard;

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Hope this helps.