My aunt who is in her 70's and lives alone carries her mobile cellular phone with her everywhere. Last week her knee gave out at the top of the stairs and she flipped over backwards and rolled down the stairs and her phone popped out of her pocket and shattered on the floor. Fortunately she had triple play installed on her cable, so she was able to crawl to a fixed wired phone to call for an ambulance. Many cable companies are actually charging more if you don't have a phone installed.
There are a number of very inexpensive services that can back up your cellular phone. Google Voice costs nothing to operate, and can be installed on computers and cheap phones that can be put in good places. Magic Jack is cheap and
RingPlus is inexpensive. Battery backups are also good ideas.
Even "plain old telephone service" with no long distance is fairly inexpensive.