OT: need a wireless pager/intercome for my grandmother

Hi,

My family is in dire need of a wireless pager/intercom for my grandmother. She needs assistance throughout the day and we need to be able to get to her within five minutes. The best solution would be three wearable devices. My grandmother could wear the base device to page the other two devices. The pageable devices need to be able to wake someone up.

I'm doing the research and will find something that appears to work, but I'm guessing someone here has already had to solve the problem I'm having. I would rather have a recommendation from a technically savvy person.