Medical alert devices that work well in Boynton Beach?

So my mom's been living in Boynton Beach for a while now and she’s had a couple stumbles lately. Nothing serious yet but I can see her losing a little bit of balance, and it’s starting to worry me. I started looking into medical alert devices and Bay Alarm Medical Alert kept coming up. It seems good but I really need to know if it actually works well in Boynton Beach. Does the signal stay strong if she’s out in the yard or walking to the mailbox? Anyone here using one locally? I really wanna make sure it’s not just another device that fails when you need it most.