Because currently usually smartphones are used for 3G connectivity with laptops and nettops on the rise for usage with 3G connectivity. If your NIT provides you [the] features a smartphone nowadays provides you (think also about e.g. PIM) then you won't need a smartphone anymore. This saves you cost on otherwise buying a smartphone, giving your purchase of NIT ('900') more value. At worst, VoIP doesn't work well, and you'd need a (simple) phone to phone with. Because you won't need 3G for it (NIT already has it) nor many other smartphone features (NIT already has it), this would potentially be a mere cheap investment, again, giving value to your NIT purache.