I want to share with you my experience. I hope that someone could help me here. I use the Ajax security system and it works without wi-fi. It uses its own sim card and it looks more reliable than cable systems. Once my friend's house was robbed after the robbers just cut the cables and there was not any signal. So, I truly recommend everyone who is going to install a new security system - use only wireless and no wi-fi ones. By the way, I am using only cameras and now I am thinking about some other devices. Can you recommend me some nice detectors to have the maximum control in my house?