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 might have been 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.

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.