Meanwhile, Uganda, Ivory Coast and Cameroon notch up strong subscriber growth.
President Uhuru Kenyatta, speaking in Qatar, says government is studying the transfer market.
Device, which goes on sale in May, features a 6-inch screen and has a five megapixel camera.
Mobile instant messaging service has 13 million users in the West African country.
Managing director of Net1 Mobile Solutions, Philip Belamant, says it is “business as usual”.
Financial institution plans to distribute 300,000 smartphones free of charge to retailers.