I found out today, why all of this occurred, last week. Apparently, someone decided to go through all the phone bills and get rid of the extra lines that "aren't being used". So, if they didn't recognize the number, they had it disconnected. They did this several months. The phone company was a little lax in disconnecting all of the lines. The one connected to our fire alarm, was only disconnected, last week.
So when it got disconnected, the alarm went off. Our phone contractor came in and said the problem was with the lines being crossed, so he disconnected my phone line and put it on the fire alarm.
Now everything is back and running.