There are a number of medical alarm options out there that target the elderly and disabled population. You should know that there are also devices that do not go directly to a monitoring center and instead directly dial 911. These are typically cellular and VoIP systems.
With cellular systems, they are not directly tied to a specific address because they are mobile and can go anywhere. This means you would have to rely on either the person using the device to know exactly where they are OR the phone giving 100% accurate GPS coordinates. This can be an issue in rural areas due to poor cellular service, and also in heavily populated areas such as an apartment complex or high rise building. Current technology only provides latitude and longitude without altitude.
If you use a device that is monitored by an alarm company they should preemptively solicit valuable information from you that would be available to pass to the 911 dispatcher should the need arise. This will allow responders to have a better location and nature of the incident if the patient is unable to talk or can’t be heard for any reasons.
Understand how your device works and make sure that they will be able to provide help when you need it most. The worst time to find out if your device will get you help is the moment when you need the help. A few questions and a little research can help in making the right decision.
Source credit: Grand Traverse 911