Remembering USSD codes can be a pain. Now you don't have to.
Here's a guide to common Safaricom Kenya ussd codes and call forwarding.
When Busy
Divert to another number, dial *670*<Number># To divert to your voicemail – Dial *670*722122# To deactivate dial ##67#
When Unanswered
To divert to Voicemail – Dial *61*0722122# To Deactivate – Dial ##61#
When Unreachable
Divert to another number, dial *620*<Number># To divert to your voicemail – Dial *620*722122# To deactivate Dial ##62#