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A smartphone actually makes calls because it is still a phone. People who buy smartphones want a convergence device; they want to be able to carry a Swiss Army Knife of communications gear. For some people, the phone part is of so little importance that they carry a basic but reliable dumbphone and pay for the added expense of a 3G/4G tablet or laptop.
I think the smartphone as a reliable phone is still a very important device, and manufacturers/OS vendors should never put the phone functions second to the data functions. If they do, they should market the device as a data terminal first, with a phone thrown in, kind of how Palm did with the Tungsten W (a really nice device that I had the pleasure of owning back in the day).