[Skunkworks] DOMESTIC ROAMING?

Fellow Geeks & Geekreses, Something interesting has been happening on my (cheap)phone lately. Each time I'm beyond the reach of my service provider(Safaricom), my phone automatically connects to another network(Orange). Please note that it doesn't display 'Orange' on my screen but rather the normal 'Safaricom'. The reason why I discovered it had switched to the Orange network was because I did some serious 'low-level' Android tinkering only to find an error that read, 'The network you selected(Orange) is out of reach' . Anybody here knows whether we have such a thing as 'domestic roaming' in Kenya or is my (cheap)phone just being mischievous? :) -- Kind Regards, Moses Muya.