I use Capital Security. They installed my system 5 years ago and it was free. Monthly fee was 30, but after 3 year contract expired, they reduced it to 20.
But that free set only include 2 contacts, 2 motions (I think). If you need more, you need to pay extra. I know I paid extra because I have an extra door. When I had mine installed, they had some promotion going on so I got a smoke alarm and remote control (to the key pad) as bonus.
Response time, well, they are really fast. A couple of times I left stuff burning on the stove and they called me almost at the same time the smoke alarm went off.
613-744-1194. Small company. Owner name is George.