PETERSON AIR FORCE BASE, Colo. — Some kids who call NORAD on Christmas Eve to find out where Santa is hang up as soon as a volunteer answers the phone — probably because they expected a recording and not a real person, veteran Santa trackers say.

There were some especially awed kids Friday, when one of the people answering the phone was first lady Michelle Obama.

A telephone link from Hawaii, where the Obamas are on vacation, allowed her to pitch in with volunteers at Peterson Air Force Base, Colo., who were answering phone calls and e-mails for the North American Aerospace Defense Command’s Santa-tracking program.

"I was ecstatic because I was talking to the president’s wife," said Evan Race, 10, of Springfield, Ill. He and his family were in North Carolina for the holidays when they decided to call NORAD.

"I was really surprised," said his 8-year-old sister, Anna. Seven-year-old Colin Race also got to talk with Obama.

The White House said she took calls for 40 minutes and spoke with children from at least a dozen families.

It’s believed to be the first time in the 55-year history of the event that a first lady joined in, said Jamie Graybeal, NORAD’S deputy chief of staff for communications.

NORAD Tracks Santa, the official name of the program, began in 1955 when a Colorado Springs newspaper ad invited kids to talk to Santa on a hotline. The phone number had a typo, and dozens of kids wound up dialing the Continental Aerospace Defense Command in Colorado Springs, the predecessor to NORAD.

The officers on duty played along and began passing along reports on Santa’s progress. It’s now a cherished ritual at NORAD, a joint U.S.-Canada command that monitors the North American skies and seas from a control center at Peterson.

"It’s really ingrained in the NORAD psyche and culture," said Canadian Forces Lt. Gen. Marcel Duval, the deputy commander of NORAD, who pitches in to field French-language calls on Christmas Eve. "It’s a goodwill gesture from all of us, on our time off, to all the kids on the planet."

Duval is careful to say that tracking Santa doesn’t interfere with the work of watching out for enemy threats to the North American continent.

Last year, NORAD Tracks Santa answered 74,000 calls and 3,500 e-mails, and organizers expect to top that this year.

Although the program is aimed at children, the volunteers answering the phones have a welcome bit of news for parents, too: St. Nick won’t stop at homes unless all the kids are asleep.

Volunteer Liz Anderson said that when she tells kids that, she will sometimes hear parents say, "See! I told you."

It takes four months of planning to marshal the 1,200 volunteers, 100 telephones, 30 laptops and two big projection TV screens the exercise requires, NORAD spokeswoman Joyce Frankovis said. All the labor is volunteer. Google, Verizon, Air Canada, defense contractor Booz Allen Hamilton and others chip in.

On Friday, volunteers answered calls and e-mails in two conference rooms in a building not far from NORAD’s headquarters. In a separate room, a three-member team fired out tweets and Facebook updates, checking against a schedule marked with a secrecy warning that said "Santa’s Eye Only."

Civilian and military staff wore blue Santa hats with "Special Operations Elf" written on the white trim.

"It is tremendously fun," said Jim Jenista, NORAD’s deputy chief for joint training exercises who has been volunteering to answer the phones for nearly a decade.

NORAD insiders drop hints about how they track Santa — "ultra-cool, high-tech, high-speed digital cameras," radar, satellites and Canadian Forces fighter jets.

But any inquiry into the technological particulars is met with a polite rebuff and a cryptic explanation involving the magic of Christmas.

The NORAD tradition is one of the few modern additions to the centuries-old Santa Claus story that have stuck, said Gerry Bowler, a history professor at the University of Manitoba and the author of "Santa Claus: A Biography."

Most embellishments never capture the public’s imagination because they tend to be ad campaigns or movies that try to "kidnap" Santa for commercial purposes, Bowler said.

NORAD, by contrast, takes an essential element of the Santa Claus story — his travels on Christmas Eve — and looks at it through a technological lens, Bower said.

"It brought Santa into the 20th century," he said.

And into the 21st century. NORAD Tracks Santa now has a Twitter account, a Facebook page, a Youtube channel and apps for mobile phones, along with a website, www.noradsanta.org, and the phone line, 877-HI NORAD.

More than 13 million unique visitors went to the website last December. NORAD Tracks Santa more than 625,000 "likes" on Facebook by Friday and more than 49,000 followers on Twitter.

The phone line is still at the core of NORAD Tracks Santa. Volunteers answer calls in two-hour shifts from 2 a.m. Mountain Time on Christmas Eve until 3 a.m. Christmas Day.

Occasionally an e-mail or phone call pleads for help. A girl from Australia wrote Friday to ask if Santa could help doctors cure her younger brother’s cancer, adding that she feared he might not live until next Christmas.

Those requests are handled "with as much hope and optimism as we can," said Graybeal, the deputy chief of staff for communications. "We promise to pass on these e-mails to Santa."

NORAD’s brass, including Duval and the commander, U.S. Adm. James A. Winnefeld Jr., did nearly back-to-back broadcast interviews on Friday morning, most of them on TV.

During one, Winnefeld moved easily from discussing Santa to discussing terrorism and back to Santa again. He ended the interview with a gentle admonition: "Have a great Christmas and go to bed on time, because Santa only visits houses where kids are sleeping."