Inspiration:

While walking on the sidewalk in New York, Steve saw a man dressed in a business suit approaching him and seemingly engaged in conversation with himself.  Since people talking to themselves on a public street would usually be among those whose "reality" was a bit different than the norm, Steve became a bit apprehensive.  He realized as the man got closer, however, that he was talking on a cell phone using a headset.  It was the incongruity of a person who may not be in touch with reality, but dressed in a business suit that sparked the idea for Cell.