This is the emergency notification system (reverse 9-1-1) from the Plymouth County Sheriff's Department. It's used by plymouth county police departments to send out emergency broadcasts like shelter locations for big snow storms or missing kids or police have suspect in the woods stay inside your house kinda stuff.
We are under an air quality alert here because of wildfires in Quebec. While we didn't answer the call, after reading your posts, I am wondering if it was an ermergency message about that. All the ID said was the number and Plymouth