When the cell phone network is down, telephones expend energy constantly searching for a connection. This can increase your battery drain. If you are in a situation where you know the network is not functioning, I recommend you set your smart phone to “Airplane Mode”. This disables all radio communication functions of your phone and allows it to act as a hand held computer thus no longer wasting power trying to contact a network that is not functioning. – Mike in Kentucky
Being a techie/having worked in a cell store, I enjoyed Kelly’s article. What I would like to add in the plethora of apps presented is a (usually) free PDF viewer. Some have searchable features, but the survival-based resources you can find in PDFs is astounding. All the Army Field Manuals, tips on canning, old household encyclopedias, gardening advice, etc.
And do no disregard phones without a micro SD card. It is quite easy to transfer files to a smart phone without one. If you have a smaller internal memory, you might have to do with less games and music and more stuff that saves your bacon! – Jim S.