Remember the commercials?
LIFE ALERT official website - I've fallen and I can't get up!(R)
But 911 can find your location. It may take some work however if they couldn't, then kids could be calling 911 fake calls and bomb threats from California to a house in Texas. SWATing happens, but its more complex and not silence or off-speech.
Many people use wifi in their home, and when you call from home it uses your wifi instead of your cell service. I do this.
People get found in the woods all the time with just by the cell phone.
So, bottom line, if you are alone and something happens and you can call 911, do it and then leave the phone on. If you can't, and maybe you are at risk, then think of getting something like the 'I've falling and I can't get up' stuff. I mean, if you stroke out then what makes you think you can dial 911?