Medical alert systems—where the press of a wearable call button puts you in touch with a dispatcher who can summon emergency help or contact a friend or family member—may offer some reassurance. If you’re considering such a system, which should you choose? The wide variety of features, service options, and fees can make it challenging to figure out what’s best for you. You might wonder whether you can simply rely on the technology you already have, such as a smartphone. Probably not, experts say. That’s because it’s unlikely that you have your smartphone with you all the time. And if you’re considering a digital assistant, such as Amazon’s Alexa, for this purpose, note that it may not have all the features you need. For example, Alexa and Google Home can dial landline and mobile phone numbers. But right now, neither can call 911, which medical alerts can do. Consumer Reports offers expert advice you need before you purchase a medical alert system, and a breakdown of the features and costs of eight companies’ offerings.