How do you get to Carnegie Hall? Practice.
How do you get to the Oval Office? Wikipedia.

When Vífill Atlason, a 16-year-old high school student from Iceland, decided to call the White House, he could not imagine the kind of publicity it would bring.
Introducing himself as Ólafur Ragnar Grímsson, the actual president of Iceland, Atlason found President George W. Bush’s allegedly secret telephone number and phoned, requesting a private meeting with him.
“I just wanted to talk to him, have a chat, invite him to Iceland and see what he’d say,” Vífill told ABC News.
A White House official, who asked not to be identified, denied the young man had accessed a private number but instead dialled 202-456-1414, the main switchboard for the West Wing.
Vífill’s mother, Harpa Hreinsdottir, a teacher at the local high school, said her son did, in fact, get through to a private phone.
“This was not a switchboard number of any kind,” she told ABC News, “it was a secret number at the highest security level.”
Vífill claims he was passed on to several people, each of them quizzing him on President Grímsson’s date of birth, where he grew up, who his parents were and the date he entered office.
“It was like passing through checkpoints,” he said. “But I had Wikipedia and a few other sites open, so it was not so difficult really.”