A missing hiker refused to answer repeated phone calls from a worried rescue team because they thought it could have been a cold caller.
The climber on Mount Elbert, Colorado, caused panic when they didn't return for 24 hours.
The hiker, who has not been named, had been reported missing on October 18 at and was found the next morning, officials said in a statement.
Lake County Search and Rescue say they started their search as they normally do - calling the person they are hunting for.
But it turned out they saw the incoming calls but ignored rescuers' attempts to make contact because "they didn't recognise the number".
The hiker was reported overdue at about 8pm on Oct. 18, according to a statement.
Eventually, they returned home some 24 hours later.
But after Lake County Search and Rescue searched multiple areas for the hiker, they say their time could have been saved.
They uploaded the account to facebook to spread the message about putting mobile phones to good use.
It read: "The subject stated they’d lost the trail around nightfall and spent the night searching for the trail, and once on the trail, bounced around onto different trails trying to locate the proper trailhead, finally reaching their car the next morning.
"They had no idea that SAR was out looking for them.
"One notable take-away is that the subject ignored repeated phone calls from us because they didn’t recognise the number."
The statement continued. "If you’re overdue according to your itinerary, and you start getting repeated calls from an unknown number, please answer the phone; it may be a SAR team trying to confirm you’re safe!
"Please remember that what seems like common sense in hindsight is not obvious to a subject in the moment when they are lost and panicking.
"In Colorado, most folks who spend time outdoors have a good understanding of the SAR infrastructure that is there to help them, but this is not the case nationwide."
