Medicaid will pay for them. Always seen monthly fees. I had 2 different companies. They go off when you sit down. Some can leave the house. They are the better ones.

I actually order these for clients who have history of falling or just fear of it. I had not heard of ones without monthly fee, as the fee is for the monitoring.
When you hit the button, a representative from the company comes on the speaker of the monitoring device and asks what type of asstance is needed. If no one answers they usually callpolice/EMTs. They also call the emergency contact
If the person says they fell but got up they may call emergency contact. depending on instructions set up initially. They also call monthly to have the customer text the unit that the battery is ok.

They used to require land line, but now they have monitoring units that work on cellular. I don't know how one without this would work, unless just programmed to call emergency contact. It has also been used when someone thinks someone is breaking in.

Some years back they came out with one that automatically went off if someone fell, but unable to push button, it had a button also. I arranged that for a few clients. It said it had few false alarms. My client never had to use it, but his wife felt better him having it when she went to the store.