And how many times have I heard about the terrible cell reception in that area? (Lauren Scharf just mentioned it in her last video.)
One thing I’ve learned from living in BFE myself is that I can always send TEXTS but I can’t make calls or FT ... so my family texts me rather than call. If I know a call is coming I often have to go outside to receive it. So I’m going to assume that this is what actually set off the major alarm ... girls planned a FT with Mom for Mothers Day and she didn’t respond. She could have been “missing” since daughters left on trip, with someone else texting for her. MOO and not really opinions but rather speculations.
When you initiate a voice call or SM, and it goes right through, your phone would have already been recognized (or pinged) by the tower cell. If a tower cell is available, but your phone had not yet "pinged", it takes one full minute for the recognition to take place. So you can sometimes be in "dead zone", hang up and wait a minute, recall and have it go through.
When you text and are not pinged by a tower cell, you are notified on your phone; but your phone keeps trying to establish a connection at pre-set intervals within the phone's programming and will attempt send for up to ten days before ceasing. At that point, most carriers will send a message telling you that the attempt has been terminated, which few people understand, and therefore just delete as random nonsense.
Verizon has pretty cell coverage all the way up Monarch's east slope, but it is from a single tower cell that is narrowly focused on the thin line of the highway itself Her house sits at the edge of that cell. AT&T has spotty coverage up Highway 50, from a mountain top tower designed to provide minimal coverage blanketing to as many places as possible. It does not show that the cell reaches her house. All other carriers use one or both of those services on the east slope of Monarch.
If SM left Sunday morning to ride a road bike up to the top of Monarch and back down on US 50, she should have taken her cell phone. If she left on a mountain bike to do off-roading, her phone would have been as useless as a rock for call or text, and she would have good cause to leave it at home.
Further, All transmission to or from a cell phone is recorded for billing or troubleshooting purposes. The exact air distance from the tower cell to the phone is recorded. The automatic "pings" are also distance-logged. So, if she had ridden her road bike up Highway 50, LE could create an arc from the tower cell that is the distance to her phone, with the arc being the approximate length of the cell coverage. Where that arc crossed US 50 would have been her exact location, within a 30 foot radius.
down in the valleys, there is better, often overlapping coverage. It becomes practical to at least get an idea of where someone with a cell phone was driving. When you get to a high density area like Denver, precise movement can be traced, walking riding or driving by triangulation of the arcs from multiple tower cells.
All of this is my opinion. Cell coverage is changing every day. Even if I was 100% accurate when I started entering this post, the information is outdated now.
JMO