So, now you're lost

Let’s talk about the viral post advising folks to change their voicemail when lost and low on cell phone battery power or their phone is dead.
Posts like this get your attention, get liked by people who don't know better, are shared by folks trying to be helpful, and the algorithm spreads it like wildfire.
  1. Without a signal (connection to the cell system) YOU CAN'T CHANGE YOUR VOICEMAIL. The voicemail system resides with your cell provider. To change your outgoing message, you have to CALL into your voicemail and then navigate the menus, record a new greeting, confirm the new greeting, etc. YOU CANNOT DO THIS WITH NO SIGNAL.
  2. If your battery is low do not waste its power by calling your voice mail—or calling or texing a friend or relative. Call 911 for help.  Calling 911 activates technology specifically designed to pinpoint your location using your phone's GPS.
  3. If you have no signal, text for help to 911. Many, if not most, 911 centers can receive a text message. An added bonus is that your GPS location will be appended to the text to 911.
  4. Text takes much less power, is far more likely to get through, will automatically retry many times if you have spotty service, leaves record others can see and can give you an indication that it got thru. By the way, because of the automatic retries, you can compose and hit send on a text and then get your phone as high as possible to improve the chances of getting the message out.
  5. Stay put. Okay, if you're lost or broken down and you've called for help (assuming you have signal and battery) please stay in one location—UNLESS YOU MUST MOVE FOR SAFETY REASONS. Changing your location makes our job more difficult. Trying to reach someone whose GPS location we have (within a circle, of course) is faster for us than trying to nail down a moving target. STAY PUT.
  6. Maximize battery life. In order to make the battery last longer, turn off everything you do not need. Close all apps. Turn off WiFi and Bluetooth. Don't use your cell phone as a GPS/map device and especially do not use the compass if your phone has one -- the compass feature in some phones is a serious battery drain. Pull out your map and compass and/or use a dedicated GPS unit. You may be instructed, by text, to turn your phone off and text back at a specific time. Also, keep your phone just a little warm with some body heat or a handwarmer.
  7. As always, tell family and friends where you are going and what time you plan to return.  Time is of the essence if you are lost and/or injured.
  8. Stay on trails or roads.  You might think that climbing up "that" hill will get you better cell phone signal.  Chances are that it won't and you will make yourself more difficult to locate and you may injur yourself in the process.
  9. Some folks may be concerned that they will get billed for being rescued so they don't call 911.  This is not the case in Arizona (except in instances of negligence e.g. crossing a flooded wash).