My wife used to be a cellular 911 operator, and where she worked she got most, if not all, of the 911 calls from Yosemite. After transferring those calls to the NPS in Yosemite she was required to listen in, in case the NPS lost their end of the call. The rangers evaluated each call, if it was not, in their opinion, a "real" emergency ("mister ranger, it got dark, we don't have a flashlight, and we ran out of candy bars, come get us"), the ranger would tell them to stay put for the night and walk out in the morning when the sun came up. No cost to the taxpayers on that one...