Our landline phone service has been disconnected since Oct 2012. We also cancelled ADT which was thorough our phone line at the same time. Our phone rang until answered on 05/15/2014 at 9am and again on 05/19/2014 at 845pm. There is only silence on the other end (dead)... contacted Century Link they can't explain this. When our phone rings it also rings in through our ADT control panel. Any thoughts on why this is happening? I keep the phone connected to the jack because I don't like the looks of the exposed jack on my kitchen wall.

Years ago when we moved to where I live now, the phone would ring and there would be nobody on the line. We figured someone was giving us crank calls. Eventually it got to the point where you would pick up the phone and could hear someone talking to someone else. The phone company finally discovered that there was a problem in their switching box (don't know the technical term) up the road. Our line was crossed with someone else somehow but it was only enough to spike the ringer when they would get a call and then got to where we could hear them but not clearly. As it turns out, when our phone rang, theirs did too.

Party line (telephony) - Wikipedia, the free encyclopedia

Its quite common, and removing the cord from the phone jack will stop the annoying ringing until the phone company can resolve this issue.