The phone rings, and a recorded or live person promises to send you a free medical alert device that summons help when you have a medical emergency. Then before long, a telemarketer convinces you to pay a monthly monitoring fee of around $35 or more. But the phony medical-monitoring company doesn’t send any device and starts billing your credit card or bank account. In some cases of this widespread scam, you’re told that a family member purchased the device for you or that your doctor ordered it for you and that it’s covered by insurance.

Although legitimate medical alert companies exist, they typically charge you for these emergency devices and never engage in unsolicited ­telemarketing.

Self-defense: When you get a robocall offering this sort of device, resist the urge to select the “opt out” key press option, which would just tell the scammers that your phone number is valid and would result in more calls. Hang up without pushing any phone buttons and without offering any information about yourself. You can call the Federal Trade Commission at 877-FTC-HELP to report a complaint, providing as many details as possible, including the caller’s phone number if it appears on your caller ID.