What If Watson Said "No"?

When Alexander Graham Bell invented the telephone, he made his first call to his assistant, Watson, using those immortal words, "Come here, Watson. I need you."

We assume that Watson answered the call, and did as he was bid. And the rest, as they say, is history.

But what would have happened if Watson ignored the call? What would have happened if he sent it to voice mail? What if a gatekeeper picked it up, and said "I'm sorry. He's not interested?" Where would we be today?

Of course, we assume that Bell would have persisted.