We have purchased a 35 year old home with an existing wired security system. The system is not acive and we believe we have the basic codes needed to reactivate. We are able to turn the door chimes on and off when needed, etc. The decision we are trying to make is, should we try to retrofit the existing wired system. We currently have2 control panels, 5 door sensors, 2 motion sensors and a whole house siren (somewhere, because we accidentally set it off). We would only preserve the exsiting wired system if 1) it improved security 2) it provided substantial cost savings. But do not want to prohibit use of any alarm.com features or smart home integrations. We prefer to DIY this to save on the costs of install.
I am including a few pics of what we are working with. I appreaciate the advice.