OT: need a wireless pager/intercome for my grandmother

[jeffslists]

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.