Had a subscriber in the country with a panic dialer. All you had to do was take the phone off the hook and the dialer would dial the seven digit police number (pre 911 service). I was stumped that every time I tried to make a test call on there line they would start dialing. also had a three digit (324) test number. If we left it Idle it would ring about twice an hour from wrong dialing. If the emergence number was seven digits (say 911-7733) it would stop a lot of the wrong numbers.