Hello,
This depends. Are you going to make just a few calls or are you going to be in Kenya for a longer period? Also, I don’t know what your hotel would charge to access an outside line. In my experience hotels charge quite hefty fees for just about any extra service.
Big wireless providers have service in Kenya. I would go to them and ask for a solution. Here’s one:
https://telkom.co.ke/
Click on the link above and look for ‘Mobile/International rates’. If you’re going to be in Kenya for a year or less I would go with a PAYG (pay as you go) plan because it doesn’t require signing a contract. After doing the currency exchange from local currency into US dollars I believe they charge about 20 cents/min to call the US with a PAYG plan. A cheaper way to call would be to use a smart phone with a WIFI connection and place calls via Skype or other VoIP service. Or you could call via Orange if they provide reasonably priced broadband service.