Where to find a wearable device that will send an alert to a phone?

If its position changes drastically (i.e. if the wearer falls down). My Dad has dementia and wouldn't be able to remember to push an alert button if he's fallen and can't get up. I'm looking for something that will sound an alert that's audible in the immediate vicinity but also that sends an alert to a phone in case no one is around.

Thank you,
Margo T.