This 100-year-old deal birthed the modern phone system. And it’s all about to end.

One hundred years ago Dec 19, one man sent a letter that would transform the telephone industry. The letter gave rise to the country's last and most powerful monopoly. And like the Internet of this century, it gave millions of ordinary people the chance to stay in touch more easily than they ever had before. The letter's author was Nathan C. Kingsbury -- a vice president of AT&T many have since forgotten. But his 1913 correspondence rapidly made its way from Kingsbury’s desk to the attorney general's, and soon after, to President Woodrow Wilson's. Wilson's administration was threatening a legal assault on AT&T. The telephone company had been aggressively buying up its competitors around the country -- maybe too many. Perhaps AT&T should be broken up, Wilson mused. Perhaps the government should take control. Then came Kingsbury's letter. In under 900 words, Kingsbury smoothed everything over. The White House’s antitrust concerns were resolved practically overnight. But the letter's impact can still be felt today.