Hi Folks...
Search and Rescue member here, telecom expert and host of the SAR prevention AdventureSmart series.
This meme, which has been circulating for years, is dangerously incorrect.
1) if your phone has no signal you can't change your voicemail
2) if your phone is low on battery voicemail is a waste of battery
Instead, please try to call 9-1-1 (or the emergency number where you are like 1-1-2, etc).
Here's why 🧵:
9-1-1 will:
1) work on ANY cell tower, even if your carrier doesn't have service there
2) automatically send your location to emergency services
3) dispatch emergency services if your battery goes out.
Stay put in a safe place. Don't risk injury or getting even further lost.
But your phone may not work AT ALL (broken, no battery, no service). It's important that you told your trusted contact where you were going BEFORE your trip. DON'T USE VOICEMAIL.
Vee... On behalf of Search and Rescue teams across the world I would ask that you edit the text above your graphic to point out that this is a discredited tip and if people are looking for tips to point them towards
https://www.adventuresmart.ca/the-three-ts/#tripplanning
Or some other credible source of information for rescue situations
Scott M. 
Willis Lisa