BTW I did miss one negative involving this type of "all in one" system. They are easy to defeat by snatching them off the wall. FWIW as long as you mount them in a central location in the house, you should be cool. They have a 15 second delay before they dial out. Also, it is possible to add a wireless keypad to my system that will allow you to place the main unit wherever you want or you can just use the remote. There are newer wireless systems that have addressed this problem completely with wireless keypads and wireless sirens.
http://www.youtube.com/watch?v=pv65r...feature=relmfu